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Zhao M, Zhang S, Wan W, Zhou C, Li N, Cheng R, Yu Y, Ouyang X, Zhou D, Jiao J, Xiong X. Coxiella burnetii effector CvpE maintains biogenesis of Coxiella-containing vacuoles by suppressing lysosome tubulation through binding PI(3)P and perturbing PIKfyve activity on lysosomes. Virulence 2024; 15:2350893. [PMID: 38725096 PMCID: PMC11085968 DOI: 10.1080/21505594.2024.2350893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 04/27/2024] [Indexed: 05/12/2024] Open
Abstract
Coxiella burnetii (C. burnetii) is the causative agent of Q fever, a zoonotic disease. Intracellular replication of C. burnetii requires the maturation of a phagolysosome-like compartment known as the replication permissive Coxiella-containing vacuole (CCV). Effector proteins secreted by the Dot/Icm secretion system are indispensable for maturation of a single large CCV by facilitating the fusion of promiscuous vesicles. However, the mechanisms of CCV maintenance and evasion of host cell clearance remain to be defined. Here, we show that C. burnetii secreted Coxiella vacuolar protein E (CvpE) contributes to CCV biogenesis by inducing lysosome-like vacuole (LLV) enlargement. LLV fission by tubulation and autolysosome degradation is impaired in CvpE-expressing cells. Subsequently, we found that CvpE suppresses lysosomal Ca2+ channel transient receptor potential channel mucolipin 1 (TRPML1) activity in an indirect manner, in which CvpE binds phosphatidylinositol 3-phosphate [PI(3)P] and perturbs PIKfyve activity in lysosomes. Finally, the agonist of TRPML1, ML-SA5, inhibits CCV biogenesis and C. burnetii replication. These results provide insight into the mechanisms of CCV maintenance by CvpE and suggest that the agonist of TRPML1 can be a novel potential treatment that does not rely on antibiotics for Q fever by enhancing Coxiella-containing vacuoles (CCVs) fission.
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Affiliation(s)
- Mingliang Zhao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Shan Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Weiqiang Wan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- College of Life Sciences, Southwest Forestry University, Kunming, Yunnan, China
| | - Chunyu Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- School of Public Health, Mudanjiang Medical University, Mudanjiang, Heilongjiang, China
| | - Nana Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- School of Public Health, Anhui Medical University, Hefei, Anhui, China
| | - Ruxi Cheng
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yonghui Yu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xuan Ouyang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jun Jiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaolu Xiong
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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2
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Mitra C, Winkley S, Kane PM. Human V-ATPase a-subunit isoforms bind specifically to distinct phosphoinositide phospholipids. J Biol Chem 2023; 299:105473. [PMID: 37979916 PMCID: PMC10755780 DOI: 10.1016/j.jbc.2023.105473] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 10/31/2023] [Accepted: 11/06/2023] [Indexed: 11/20/2023] Open
Abstract
Vacuolar H+-ATPases (V-ATPases) are highly conserved multisubunit enzymes that maintain the distinct pH of eukaryotic organelles. The integral membrane a-subunit is encoded by tissue- and organelle-specific isoforms, and its cytosolic N-terminal domain (aNT) modulates organelle-specific regulation and targeting of V-ATPases. Organelle membranes have specific phosphatidylinositol phosphate (PIP) lipid enrichment linked to maintenance of organelle pH. In yeast, the aNT domains of the two a-subunit isoforms bind PIP lipids enriched in the organelle membranes where they reside; these interactions affect activity and regulatory properties of the V-ATPases containing each isoform. Humans have four a-subunit isoforms, and we hypothesize that the aNT domains of these isoforms will also bind to specific PIP lipids. The a1 and a2 isoforms of human V-ATPase a-subunits are localized to endolysosomes and Golgi, respectively. We determined that bacterially expressed Hua1NT and Hua2NT bind specifically to endolysosomal PIP lipids PI(3)P and PI(3,5)P2 and Golgi enriched PI(4)P, respectively. Despite the lack of canonical PIP-binding sites, we identified potential binding sites in the HuaNT domains by sequence comparisons and existing subunit structures and models. We found that mutations at a similar location in the distal loops of both HuaNT isoforms compromise binding to their cognate PIP lipids, suggesting that these loops encode PIP specificity of the a-subunit isoforms. These data suggest a mechanism through which PIP lipid binding could stabilize and activate V-ATPases in distinct organelles.
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Affiliation(s)
- Connie Mitra
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Samuel Winkley
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA.
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3
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Bhowmick SS, Mahajan SK, Shah V, Kashyap K. Unmistakable Truncal Dystonia Mistaken as Psychogenic: A Case Report of VAC14-Related Neurodegeneration. Mov Disord Clin Pract 2023; 10:S15-S20. [PMID: 37636228 PMCID: PMC10448624 DOI: 10.1002/mdc3.13776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/09/2023] [Accepted: 04/03/2023] [Indexed: 08/29/2023] Open
Affiliation(s)
- Suvorit Subhas Bhowmick
- Movement Disorders ClinicVadodara Institute of Neurological SciencesVadodaraIndia
- Neurology ClinicSir Sayjirao General HospitalVadodaraIndia
| | | | | | - Kriti Kashyap
- CSIR‐Institute of Genomics and Integrative BiologyDelhiIndia
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4
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Mitra C, Kane PM. Human V-ATPase a-subunit isoforms bind specifically to distinct phosphoinositide phospholipids. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.24.538068. [PMID: 37162989 PMCID: PMC10168244 DOI: 10.1101/2023.04.24.538068] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
V-ATPases are highly conserved multi-subunit enzymes that maintain the distinct pH of eukaryotic organelles. The integral membrane a-subunit is encoded by tissue and organelle specific isoforms, and its cytosolic N-terminal domain (aNT) modulates organelle specific regulation and targeting of V-ATPases. Organelle membranes have specific phosphatidylinositol phosphate (PIP) lipid enrichment linked to maintenance of organelle pH. In yeast, the aNT domains of the two a-subunit isoforms bind PIP lipids enriched in the organelle membranes where they reside; these interactions affect activity and regulatory properties of the V-ATPases containing each isoform. Humans have four a-subunit isoforms. We hypothesize that the aNT domains of the human isoforms will also bind to specific PIP lipids. The a1 and a2 isoforms of human V-ATPase a-subunits are localized to endolysosomes and Golgi, respectively. Bacterially expressed Hua1NT and Hua2NT bind specifically to endolysosomal PIP lipids PI(3)P and PI(3,5)P2 and Golgi enriched PI(4)P, respectively. Despite the lack of canonical PIP binding sites, potential binding sites in the HuaNT domains were identified by sequence comparisons and existing subunit structures and models. Mutations at a similar location in the distal loops of both HuaNT isoforms compromise binding to their cognate PIP lipids, suggesting that these loops encode PIP specificity of the a-subunit isoforms. These data also suggest a mechanism through which PIP lipid binding could stabilize and activate V-ATPases in distinct organelles.
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Affiliation(s)
- Connie Mitra
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY
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5
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Dellin M, Rohrbeck I, Asrani P, Schreiber JA, Ritter N, Glorius F, Wünsch B, Budde T, Temme L, Strünker T, Stallmeyer B, Tüttelmann F, Meuth SG, Spehr M, Matschke J, Steinbicker A, Gatsogiannis C, Stoll R, Strutz-Seebohm N, Seebohm G. The second PI(3,5)P 2 binding site in the S0 helix of KCNQ1 stabilizes PIP 2-at the primary PI1 site with potential consequences on intermediate-to-open state transition. Biol Chem 2023; 404:241-254. [PMID: 36809224 DOI: 10.1515/hsz-2022-0247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 12/13/2022] [Indexed: 02/23/2023]
Abstract
The Phosphatidylinositol 3-phosphate 5-kinase Type III PIKfyve is the main source for selectively generated phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2), a known regulator of membrane protein trafficking. PI(3,5)P2 facilitates the cardiac KCNQ1/KCNE1 channel plasma membrane abundance and therewith increases the macroscopic current amplitude. Functional-physical interaction of PI(3,5)P2 with membrane proteins and its structural impact is not sufficiently understood. This study aimed to identify molecular interaction sites and stimulatory mechanisms of the KCNQ1/KCNE1 channel via the PIKfyve-PI(3,5)P2 axis. Mutational scanning at the intracellular membrane leaflet and nuclear magnetic resonance (NMR) spectroscopy identified two PI(3,5)P2 binding sites, the known PIP2 site PS1 and the newly identified N-terminal α-helix S0 as relevant for functional PIKfyve effects. Cd2+ coordination to engineered cysteines and molecular modeling suggest that repositioning of S0 stabilizes the channel s open state, an effect strictly dependent on parallel binding of PI(3,5)P2 to both sites.
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Affiliation(s)
- Maurice Dellin
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
| | - Ina Rohrbeck
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
| | - Purva Asrani
- Faculty of Chemistry and Biochemistry, Biomolecular NMR Spectroscopy and RUBiospek|NMR, Ruhr University of Bochum, Universitätsstraße 150, D-44780, Bochum, Germany
| | - Julian A Schreiber
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
| | - Nadine Ritter
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Frank Glorius
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, D-48149, Münster, Germany
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Thomas Budde
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
- Institute of Physiology I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149, Münster, Germany
| | - Louisa Temme
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Timo Strünker
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Domagkstraße 11, D-48149, Münster, Germany
- Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Birgit Stallmeyer
- Institute of Reproductive Genetics, University of Münster, Vesaliusweg 12-14, D-48149, Münster, Germany
| | - Frank Tüttelmann
- Institute of Reproductive Genetics, University of Münster, Vesaliusweg 12-14, D-48149, Münster, Germany
| | - Sven G Meuth
- Department of Neurology, Heinrich Heine University Düsseldorf, Moorenstraße 5, D-40225, Düsseldorf, Germany
| | - Marc Spehr
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Worringerweg 3, D-52074, Aachen, Germany
| | - Johann Matschke
- Institute of Cell Biology (Cancer Research), University Hospital Essen, University of Duisburg-Essen, D-45147, Essen, Germany
| | - Andrea Steinbicker
- Goethe University Frankfurt and University Hospital Frankfurt, Theodor-Stern-Kai 7, D-60590, Frankfurt, Germany
| | - Christos Gatsogiannis
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Münster, Busso-Peus Strasse 10, D-48149, Germany
| | - Raphael Stoll
- Faculty of Chemistry and Biochemistry, Biomolecular NMR Spectroscopy and RUBiospek|NMR, Ruhr University of Bochum, Universitätsstraße 150, D-44780, Bochum, Germany
| | - Nathalie Strutz-Seebohm
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
| | - Guiscard Seebohm
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
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6
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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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7
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Rosenhouse-Dantsker A, Gazgalis D, Logothetis DE. PI(4,5)P 2 and Cholesterol: Synthesis, Regulation, and Functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:3-59. [PMID: 36988876 DOI: 10.1007/978-3-031-21547-6_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is the most abundant membrane phosphoinositide and cholesterol is an essential component of the plasma membrane (PM). Both lipids play key roles in a variety of cellular functions including as signaling molecules and major regulators of protein function. This chapter provides an overview of these two important lipids. Starting from a brief description of their structure, synthesis, and regulation, the chapter continues to describe the primary functions and signaling processes in which PI(4,5)P2 and cholesterol are involved. While PI(4,5)P2 and cholesterol can act independently, they often act in concert or affect each other's impact. The chapters in this volume on "Cholesterol and PI(4,5)P2 in Vital Biological Functions: From Coexistence to Crosstalk" focus on the emerging relationship between cholesterol and PI(4,5)P2 in a variety of biological systems and processes. In this chapter, the next section provides examples from the ion channel field demonstrating that PI(4,5)P2 and cholesterol can act via common mechanisms. The chapter ends with a discussion of future directions.
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Affiliation(s)
| | - Dimitris Gazgalis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
| | - Diomedes E Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
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Qi L, Sun C, Sun S, Li A, Hu Q, Liu Y, Zhang Y. Phosphatidylinositol (3,5)-bisphosphate machinery regulates neurite thickness through neuron-specific endosomal protein NSG1/NEEP21. J Biol Chem 2022; 299:102775. [PMID: 36493904 PMCID: PMC9823133 DOI: 10.1016/j.jbc.2022.102775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 10/31/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
Phosphatidylinositol (3,5)-bisphosphate [PtdIns(3,5)P2] is a critical signaling phospholipid involved in endolysosome homeostasis. It is synthesized by a protein complex composed of PIKfyve, Vac14, and Fig4. Defects in PtdIns(3,5)P2 synthesis underlie a number of human neurological disorders, including Charcot-Marie-Tooth disease, child onset progressive dystonia, and others. However, neuron-specific functions of PtdIns(3,5)P2 remain less understood. Here, we show that PtdIns(3,5)P2 pathway is required to maintain neurite thickness. Suppression of PIKfyve activities using either pharmacological inhibitors or RNA silencing resulted in decreased neurite thickness. We further find that the regulation of neurite thickness by PtdIns(3,5)P2 is mediated by NSG1/NEEP21, a neuron-specific endosomal protein. Knockdown of NSG1 expression also led to thinner neurites. mCherry-tagged NSG1 colocalized and interacted with proteins in the PtdIns(3,5)P2 machinery. Perturbation of PtdIns(3,5)P2 dynamics by overexpressing Fig4 or a PtdIns(3,5)P2-binding domain resulted in mislocalization of NSG1 to nonendosomal locations, and suppressing PtdIns(3,5)P2 synthesis resulted in an accumulation of NSG1 in EEA1-positive early endosomes. Importantly, overexpression of NSG1 rescued neurite thinning in PtdIns(3,5)P2-deficient CAD neurons and primary cortical neurons. Our study uncovered the role of PtdIns(3,5)P2 in the morphogenesis of neurons, which revealed a novel aspect of the pathogenesis of PtdIns(3,5)P2-related neuropathies. We also identified NSG1 as an important downstream protein of PtdIns(3,5)P2, which may provide a novel therapeutic target in neurological diseases.
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Affiliation(s)
- Lijuan Qi
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China,National Clinical Research Center for Hematologic Diseases, Jiangsu Institute of Hematology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Chen Sun
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Soochow University, Suzhou, Jiangsu, China
| | - Shenqing Sun
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China
| | - Aiqing Li
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China
| | - Qiuming Hu
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China
| | - Yaobo Liu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Soochow University, Suzhou, Jiangsu, China
| | - Yanling Zhang
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China,For correspondence: Yanling Zhang
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9
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Groth A, Ahlmann S, Werner A, Pöggeler S. The vacuolar morphology protein VAC14 plays an important role in sexual development in the filamentous ascomycete Sordaria macrospora. Curr Genet 2022; 68:407-427. [PMID: 35776170 PMCID: PMC9279277 DOI: 10.1007/s00294-022-01244-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/01/2022] [Accepted: 06/02/2022] [Indexed: 11/29/2022]
Abstract
The multiprotein Fab1p/PIKfyve-complex regulating the abundance of the phospholipid phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2) is highly conserved among eukaryotes. In yeast/mammals, it is composed of the phosphatidylinositol 3-phosphate 5-kinase Fab1p/PIKfyve, the PtdIns(3,5)P2 phosphatase Fig4p/Sac3 and the scaffolding subunit Vac14p/ArPIKfyve. The complex is located to vacuolar membranes in yeast and to endosomal membranes in mammals, where it controls the synthesis and turnover of PtdIns(3,5)P2. In this study, we analyzed the role and function of the Fab1p/PIKfyve-complex scaffold protein SmVAC14 in the filamentous ascomycete Sordaria macrospora (Sm). We generated the Smvac14 deletion strain ∆vac14 and performed phenotypic analysis of the mutant. Furthermore, we conducted fluorescence microscopic localization studies of fluorescently labeled SmVAC14 with vacuolar and late endosomal marker proteins. Our results revealed that SmVAC14 is important for maintaining vacuolar size and appearance as well as proper sexual development in S. macrospora. In addition, SmVAC14 plays an important role in starvation stress response. Accordingly, our results propose that the turnover of PtdIns(3,5)P2 is of great significance for developmental processes in filamentous fungi.
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Affiliation(s)
- Anika Groth
- Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Grisebachstr. 8, 37077, Göttingen, Germany
| | - Svenja Ahlmann
- Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Grisebachstr. 8, 37077, Göttingen, Germany
| | - Antonia Werner
- Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Grisebachstr. 8, 37077, Göttingen, Germany
| | - Stefanie Pöggeler
- Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Grisebachstr. 8, 37077, Göttingen, Germany.
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10
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Inhibition of lipid kinase PIKfyve reveals a role for phosphatase Inpp4b in the regulation of PI(3)P-mediated lysosome dynamics through VPS34 activity. J Biol Chem 2022; 298:102187. [PMID: 35760104 PMCID: PMC9304791 DOI: 10.1016/j.jbc.2022.102187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 06/13/2022] [Accepted: 06/15/2022] [Indexed: 11/21/2022] Open
Abstract
Lysosome membranes contain diverse phosphoinositide (PtdIns) lipids that coordinate lysosome function and dynamics. The PtdIns repertoire on lysosomes is tightly regulated by the actions of diverse PtdIns kinases and phosphatases; however, specific roles for PtdIns in lysosomal functions and dynamics are currently unclear and require further investigation. It was previously shown that PIKfyve, a lipid kinase that synthesizes PtdIns(3,5)P2 from PtdIns(3)P, controls lysosome "fusion-fission" cycle dynamics, autophagosome turnover, and endocytic cargo delivery. Furthermore, INPP4B, a PtdIns 4-phosphatase that hydrolyzes PtdIns(3,4)P2 to form PtdIns(3)P, is emerging as a cancer-associated protein with roles in lysosomal biogenesis and other lysosomal functions. Here, we investigated the consequences of disrupting PIKfyve function in Inpp4b-deficient mouse embryonic fibroblasts. Through confocal fluorescence imaging, we observed the formation of massively enlarged lysosomes, accompanied by exacerbated reduction of endocytic trafficking, disrupted lysosome fusion-fission dynamics, and inhibition of autophagy. Finally, HPLC scintillation quantification of 3H-myo-inositol labelled phosphoinositides and phosphoinositide immunofluorescence staining, we observed that lysosomal PtdIns(3)P levels were significantly elevated in Inpp4b-deficient cells due to the hyperactivation of phosphatidylinositol 3-kinase catalytic subunit VPS34 enzymatic activity. In conclusion, our study identifies a novel signaling axis that maintains normal lysosomal homeostasis and dynamics, which includes the catalytic functions of Inpp4b, PIKfyve, and VPS34.
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11
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Rivero-Ríos P, Weisman LS. Roles of PIKfyve in multiple cellular pathways. Curr Opin Cell Biol 2022; 76:102086. [PMID: 35584589 PMCID: PMC9108489 DOI: 10.1016/j.ceb.2022.102086] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/27/2022] [Accepted: 04/02/2022] [Indexed: 02/01/2023]
Abstract
Phosphoinositide signaling lipids are crucial for eukaryotes and regulate many aspects of cell function. These signaling molecules are difficult to study because they are extremely low abundance. Here, we focus on two of the lowest abundance phosphoinositides, PI(3,5)P2 and PI(5)P, which play critical roles in cellular homeostasis, membrane trafficking and transcription. Their levels are tightly regulated by a protein complex that includes PIKfyve, Fig4 and Vac14. Importantly, mutations in this complex that decrease PI(3,5)P2 and PI(5)P are linked to human diseases, especially those of the nervous system. Paradoxically, PIKfyve inhibitors which decrease PI(3,5)P2 and PI(5)P, are currently being tested for some neurodegenerative diseases, as well as other diverse diseases including some cancers, and as a treatment for SARS-CoV2 infection. A more comprehensive picture of the pathways that are regulated by PIKfyve will be critical to understand the roles of PI(3,5)P2 and PI(5)P in normal human physiology and in disease.
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Affiliation(s)
- Pilar Rivero-Ríos
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Lois S Weisman
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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12
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Houghton OH, Mizielinska S, Gomez-Suaga P. The Interplay Between Autophagy and RNA Homeostasis: Implications for Amyotrophic Lateral Sclerosis and Frontotemporal Dementia. Front Cell Dev Biol 2022; 10:838402. [PMID: 35573690 PMCID: PMC9096704 DOI: 10.3389/fcell.2022.838402] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 04/14/2022] [Indexed: 01/18/2023] Open
Abstract
Amyotrophic lateral sclerosis and frontotemporal dementia are neurodegenerative disorders that lie on a disease spectrum, sharing genetic causes and pathology, and both without effective therapeutics. Two pathways that have been shown to play major roles in disease pathogenesis are autophagy and RNA homeostasis. Intriguingly, there is an increasing body of evidence suggesting a critical interplay between these pathways. Autophagy is a multi-stage process for bulk and selective clearance of malfunctional cellular components, with many layers of regulation. Although the majority of autophagy research focuses on protein degradation, it can also mediate RNA catabolism. ALS/FTD-associated proteins are involved in many stages of autophagy and autophagy-mediated RNA degradation, particularly converging on the clearance of persistent pathological stress granules. In this review, we will summarise the progress in understanding the autophagy-RNA homeostasis interplay and how that knowledge contributes to our understanding of the pathobiology of ALS/FTD.
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Affiliation(s)
- O H Houghton
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom.,UK Dementia Research Institute at King's College London, London, United Kingdom
| | - S Mizielinska
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom.,UK Dementia Research Institute at King's College London, London, United Kingdom
| | - P Gomez-Suaga
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom.,Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Enfermería y Terapia Ocupacional, Universidad de Extremadura, Cáceres, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Instituto Universitario de Investigación Biosanitaria de Extremadura (INUBE), Cáceres, Spain
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13
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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.
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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
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14
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Michell RH. The reliability of biomedical science: A case history of a maturing experimental field. Bioessays 2022; 44:e2200020. [PMID: 35393713 DOI: 10.1002/bies.202200020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/25/2022] [Accepted: 03/29/2022] [Indexed: 11/10/2022]
Abstract
There is much discussion in the media and some of the scientific literature of how many of the conclusions from scientific research should be doubted. These critiques often focus on studies, typically in non-experimental spheres of biomedical and social sciences - that search large datasets for novel correlations, with a risk that inappropriate statistical evaluations might yield dubious conclusions. By contrast, results from experimental biological research can often be interpreted largely without statistical analysis. Typically: novel observation(s) are reported, and an explanatory hypothesis is offered; multiple labs undertake experiments to test the hypothesis; interpretation of the results may refute the hypothesis, support it or provoke its modification; the test/revise sequence is reiterated many times; and the field moves forward. I illustrate this experimental/non-experimental dichotomy by examining the contrasting recent histories of: (a) our remarkable and growing understanding of how several inositol-containing phospholipids contribute to the lives of eukaryote cells; and (b) the difficulty of achieving any agreed mechanistic understanding of why consuming dietary supplements of inositol is clinically beneficial in some metabolic diseases.
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15
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Giridharan SSP, Luo G, Rivero-Rios P, Steinfeld N, Tronchere H, Singla A, Burstein E, Billadeau DD, Sutton MA, Weisman LS. Lipid kinases VPS34 and PIKfyve coordinate a phosphoinositide cascade to regulate Retriever-mediated recycling on endosomes. eLife 2022; 11:69709. [PMID: 35040777 PMCID: PMC8816382 DOI: 10.7554/elife.69709] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 01/17/2022] [Indexed: 11/13/2022] Open
Abstract
Cell-surface receptors control how cells respond to their environment. Many cell-surface receptors recycle from endosomes to the plasma membrane via a recently discovered pathway, which includes sorting-nexin SNX17, Retriever, WASH and CCC complexes. Here, using mammalian cells, we discover that PIKfyve and its upstream PI3-kinase VPS34 positively regulate this pathway. VPS34 produces PI3P, which is the substrate for PIKfyve to generate PI3,5P2. We show that PIKfyve controls recycling of cargoes including integrins, receptors that control cell migration. Furthermore, endogenous PIKfyve colocalizes with SNX17, Retriever, WASH and CCC complexes on endosomes. Importantly, PIKfyve inhibition results displacement of Retriever and CCC from endosomes. In addition, we show that recruitment of SNX17 is an early step and requires VPS34. These discoveries suggest that VPS34 and PIKfyve coordinate an ordered pathway to regulate recycling from endosomes and suggest how PIKfyve functions in cell migration.
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Affiliation(s)
| | - Guangming Luo
- Department of Cell and Developmental Biology, University of Michigan-Ann Arbor
| | - Pilar Rivero-Rios
- Department of Cell and Developmental Biology, University of Michigan-Ann Arbor
| | - Noah Steinfeld
- Department of Cell and Developmental Biology, University of Michigan-Ann Arbor
| | | | - Amika Singla
- Department of Internal Medicine, The University of Texas Southwestern Medical Center
| | - Ezra Burstein
- Department of Internal Medicine, The University of Texas Southwestern Medical Center
| | | | - Michael A Sutton
- Molecular and Integrative Physiology, University of Michigan-Ann Arbor
| | - Lois S Weisman
- Department of Cell and Developmental Biology, University of Michigan-Ann Arbor
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16
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Hasegawa J, Tokuda E, Yao Y, Sasaki T, Inoki K, Weisman LS. PP2A-dependent TFEB activation is blocked by PIKfyve-induced mTORC1 activity. Mol Biol Cell 2022; 33:ar26. [PMID: 35020443 PMCID: PMC9250387 DOI: 10.1091/mbc.e21-06-0309] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Transcriptional factor EB (TFEB) is a master regulator of genes required for autophagy and lysosomal function. The nuclear localization of TFEB is blocked by the mechanistic target of rapamycin complex 1 (mTORC1)-dependent phosphorylation of TFEB at multiple sites including Ser-211. Here we show that inhibition of PIKfyve, which produces phosphatidylinositol 3,5-bisphosphate on endosomes and lysosomes, causes a loss of Ser-211 phosphorylation and concomitant nuclear localization of TFEB. We found that while mTORC1 activity toward S6K1, as well as other major mTORC1 substrates, is not impaired, PIKfyve inhibition specifically impedes the interaction of TFEB with mTORC1. This suggests that mTORC1 activity on TFEB is selectively inhibited due to loss of mTORC1 access to TFEB. In addition, we found that TFEB activation during inhibition of PIKfyve relies on the ability of protein phosphatase 2A (PP2A) but not calcineurin/PPP3 to dephosphorylate TFEB Ser-211. Thus when PIKfyve is inhibited, PP2A is dominant over mTORC1 for control of TFEB phosphorylation at Ser-S211. Together these findings suggest that mTORC1 and PP2A have opposing roles on TFEB via phosphorylation and dephosphorylation of Ser-211, respectively, and further that PIKfyve inhibits TFEB activity by facilitating mTORC1-dependent phosphorylation of TFEB.
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Affiliation(s)
- Junya Hasegawa
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.,Department of Biochemical Pathophysiology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Emi Tokuda
- Department of Biochemical Pathophysiology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Yao Yao
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA
| | - Takehiko Sasaki
- Department of Biochemical Pathophysiology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Ken Inoki
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.,Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 East Catherine Street, Ann Arbor, MI 48109, USA.,Department of Internal Medicine, University of Michigan Medical School, 1500 East Medical enter Drive, Ann Arbor, MI 48109, USA
| | - Lois S Weisman
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.,Department of Cell and Developmental Biology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109
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17
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Bouhamdani N, Comeau D, Turcotte S. A Compendium of Information on the Lysosome. Front Cell Dev Biol 2021; 9:798262. [PMID: 34977038 PMCID: PMC8714965 DOI: 10.3389/fcell.2021.798262] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/02/2021] [Indexed: 12/16/2022] Open
Abstract
For a long time, lysosomes were considered as mere waste bags for cellular constituents. Thankfully, studies carried out in the past 15 years were brimming with elegant and crucial breakthroughs in lysosome research, uncovering their complex roles as nutrient sensors and characterizing them as crucial multifaceted signaling organelles. This review presents the scientific knowledge on lysosome physiology and functions, starting with their discovery and reviewing up to date ground-breaking discoveries highlighting their heterogeneous functions as well as pending questions that remain to be answered. We also review the roles of lysosomes in anti-cancer drug resistance and how they undergo a series of molecular and functional changes during malignant transformation which lead to tumor aggression, angiogenesis, and metastases. Finally, we discuss the strategy of targeting lysosomes in cancer which could lead to the development of new and effective targeted therapies.
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Affiliation(s)
- Nadia Bouhamdani
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada
- Dr. Georges-L. Dumont University Hospital Centre, Clinical Research Sector, Vitalité Health Network, Moncton, NB, Canada
- Atlantic Cancer Research Institute, Moncton, NB, Canada
| | - Dominique Comeau
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada
- Atlantic Cancer Research Institute, Moncton, NB, Canada
| | - Sandra Turcotte
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada
- Atlantic Cancer Research Institute, Moncton, NB, Canada
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18
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Wang H, Dong Y, Wan B, Ji Y, Xu Q. Identification and Characterization Analysis of Transient Receptor Potential Mucolipin Protein of Laodelphax striatellus Fallén. INSECTS 2021; 12:insects12121107. [PMID: 34940195 PMCID: PMC8706664 DOI: 10.3390/insects12121107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/08/2021] [Accepted: 12/11/2021] [Indexed: 12/29/2022]
Abstract
Transient receptor potential mucolipin (TRPML) protein in flies plays a pivotal role in Ca2+ ions release, resulting in membrane trafficking, autophagy and ion homeostasis. However, to date, the characterization of TRPML in agricultural pests remains unknown. Here, we firstly reported the TRPML of a destructive pest of gramineous crops, Laodelphax striatellus. The L. striatellus TRPML (Ls-TRPML) has a 1818 bp open reading frame, encoding 605 amino acid. TRPML in agricultural pests is evolutionarily conserved, and the expression of Ls-TRPML is predominately higher in the ovary than in other organs of L. striatellus at the transcript and protein level. The Bac-Bac system showed that Ls-TRPML localized in the plasma membrane, nuclear membrane and nucleus and co-localized with lysosome in Spodoptera frugiperda cells. The immunofluorescence microscopy analysis showed that Ls-TRPML localized in the cytoplasm and around the nuclei of the intestine cells or ovary follicular cells of L. striatellus. The results from the lipid-binding assay revealed that Ls-TRPML strongly bound to phosphatidylinositol-3,5-bisphosphate, as compared with other phosphoinositides. Overall, our results helped is identify and characterize the TRPML protein of L. striatellus, shedding light on the function of TRPML in multiple cellular processes in agricultural pests.
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Affiliation(s)
- Haitao Wang
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; (Y.D.); (Y.J.)
- Correspondence: (H.W.); (Q.X.); Tel.: +86-134-5181-6249 (H.W.); +86-133-2781-7381 (Q.X.)
| | - Yan Dong
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; (Y.D.); (Y.J.)
| | - Baijie Wan
- Institute of Agricultural Sciences in Jiangsu Coastal Area, Yancheng 224002, China;
| | - Yinghua Ji
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; (Y.D.); (Y.J.)
| | - Qiufang Xu
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; (Y.D.); (Y.J.)
- Institute of Life Sciences, Jiangsu University, Zhenjiang 212013, China
- Correspondence: (H.W.); (Q.X.); Tel.: +86-134-5181-6249 (H.W.); +86-133-2781-7381 (Q.X.)
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19
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Gross JD, Pears CJ. Possible Involvement of the Nutrient and Energy Sensors mTORC1 and AMPK in Cell Fate Diversification in a Non-Metazoan Organism. Front Cell Dev Biol 2021; 9:758317. [PMID: 34820379 PMCID: PMC8606421 DOI: 10.3389/fcell.2021.758317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/19/2021] [Indexed: 11/13/2022] Open
Abstract
mTORC1 and AMPK are mutually antagonistic sensors of nutrient and energy status that have been implicated in many human diseases including cancer, Alzheimer’s disease, obesity and type 2 diabetes. Starved cells of the social amoeba Dictyostelium discoideum aggregate and eventually form fruiting bodies consisting of stalk cells and spores. We focus on how this bifurcation of cell fate is achieved. During growth mTORC1 is highly active and AMPK relatively inactive. Upon starvation, AMPK is activated and mTORC1 inhibited; cell division is arrested and autophagy induced. After aggregation, a minority of the cells (prestalk cells) continue to express much the same set of developmental genes as during aggregation, but the majority (prespore cells) switch to the prespore program. We describe evidence suggesting that overexpressing AMPK increases the proportion of prestalk cells, as does inhibiting mTORC1. Furthermore, stimulating the acidification of intracellular acidic compartments likewise increases the proportion of prestalk cells, while inhibiting acidification favors the spore pathway. We conclude that the choice between the prestalk and the prespore pathways of cell differentiation may depend on the relative strength of the activities of AMPK and mTORC1, and that these may be controlled by the acidity of intracellular acidic compartments/lysosomes (pHv), cells with low pHv compartments having high AMPK activity/low mTORC1 activity, and those with high pHv compartments having high mTORC1/low AMPK activity. Increased insight into the regulation and downstream consequences of this switch should increase our understanding of its potential role in human diseases, and indicate possible therapeutic interventions.
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Affiliation(s)
- Julian D Gross
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Catherine J Pears
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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20
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Wang C, Xiang Y, Qian D. Current progress in plant V-ATPase: From biochemical properties to physiological functions. JOURNAL OF PLANT PHYSIOLOGY 2021; 266:153525. [PMID: 34560396 DOI: 10.1016/j.jplph.2021.153525] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/12/2021] [Accepted: 09/12/2021] [Indexed: 06/13/2023]
Abstract
Vacuolar-type adenosine triphosphatase (V-ATPase, VHA) is a highly conserved, ATP-driven multisubunit proton pump that is widely distributed in all eukaryotic cells. V-ATPase consists of two domains formed by at least 13 different subunits, the membrane peripheral V1 domain responsible for ATP hydrolysis, and the membrane-integral V0 domain responsible for proton translocation. V-ATPase plays an essential role in energizing secondary active transport and is indispensable to plants. In addition to multiple stress responses, plant V-ATPase is also implicated in physiological processes such as growth, development, and morphogenesis. Based on the identification of distinct V-ATPase mutants and advances in luminal pH measurements in vivo, it has been revealed that this holoenzyme complex plays a pivotal role in pH homeostasis of the plant endomembrane system and endocytic and secretory trafficking. Here, we review recent progress in comprehending the biochemical properties and physiological functions of plant V-ATPase and explore the topics that require further elucidation.
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Affiliation(s)
- Chao Wang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Yun Xiang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Dong Qian
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
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21
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Yamada Y, Forbes G, Du Q, Kawata T, Schaap P. Loss of PIKfyve Causes Transdifferentiation of Dictyostelium Spores Into Basal Disc Cells. Front Cell Dev Biol 2021; 9:692473. [PMID: 34490246 PMCID: PMC8417116 DOI: 10.3389/fcell.2021.692473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 07/02/2021] [Indexed: 11/13/2022] Open
Abstract
The 1-phosphatidylinositol-3-phosphate 5-kinase PIKfyve generates PtdIns3,5P2 on late phagolysosomes, which by recruiting the scission protein Atg18, results in their fragmentation in the normal course of endosome processing. Loss of PIKfyve function causes cellular hypervacuolization in eukaryotes and organ failure in humans. We identified pikfyve as the defective gene in a Dictyostelium mutant that failed to form spores. The amoebas normally differentiated into prespore cells and initiated spore coat protein synthesis in Golgi-derived prespore vesicles. However, instead of exocytosing, the prespore vesicles fused into the single vacuole that typifies the stalk and basal disc cells that support the spores. This process was accompanied by stalk wall biosynthesis, loss of spore gene expression and overexpression of ecmB, a basal disc and stalk-specific gene, but not of the stalk-specific genes DDB_G0278745 and DDB_G0277757. Transdifferentiation of prespore into stalk-like cells was previously observed in mutants that lack early autophagy genes, like atg5, atg7, and atg9. However, while autophagy mutants specifically lacked cAMP induction of prespore gene expression, pikfyve - showed normal early autophagy and prespore induction, but increased in vitro induction of ecmB. Combined, the data suggest that the Dictyostelium endosomal system influences cell fate by acting on cell type specific gene expression.
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Affiliation(s)
- Yoko Yamada
- School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Department of Biology, Faculty of Science, Toho University, Funabashi, Japan.,Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Gillian Forbes
- School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Qingyou Du
- School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Takefumi Kawata
- Department of Biology, Faculty of Science, Toho University, Funabashi, Japan
| | - Pauline Schaap
- School of Life Sciences, University of Dundee, Dundee, United Kingdom
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22
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Levine TP. TMEM106B in humans and Vac7 and Tag1 in yeast are predicted to be lipid transfer proteins. Proteins 2021; 90:164-175. [PMID: 34347309 DOI: 10.1002/prot.26201] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 07/11/2021] [Accepted: 07/23/2021] [Indexed: 11/05/2022]
Abstract
TMEM106B is an integral membrane protein of late endosomes and lysosomes involved in neuronal function, its overexpression being associated with familial frontotemporal lobar degeneration, and point mutation linked to hypomyelination. It has also been identified in multiple screens for host proteins required for productive SARS-CoV-2 infection. Because standard approaches to understand TMEM106B at the sequence level find no homology to other proteins, it has remained a protein of unknown function. Here, the standard tool PSI-BLAST was used in a nonstandard way to show that the lumenal portion of TMEM106B is a member of the late embryogenesis abundant-2 (LEA-2) domain superfamily. More sensitive tools (HMMER, HHpred, and trRosetta) extended this to predict LEA-2 domains in two yeast proteins. One is Vac7, a regulator of PI(3,5)P2 production in the degradative vacuole, equivalent to the lysosome, which has a LEA-2 domain in its lumenal domain. The other is Tag1, another vacuolar protein, which signals to terminate autophagy and has three LEA-2 domains in its lumenal domain. Further analysis of LEA-2 structures indicated that LEA-2 domains have a long, conserved lipid-binding groove. This implies that TMEM106B, Vac7, and Tag1 may all be lipid transfer proteins in the lumen of late endocytic organelles.
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Li L, Tong M, Fu Y, Chen F, Zhang S, Chen H, Ma X, Li D, Liu X, Zhong Q. Lipids and membrane-associated proteins in autophagy. Protein Cell 2021; 12:520-544. [PMID: 33151516 PMCID: PMC8225772 DOI: 10.1007/s13238-020-00793-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 08/07/2020] [Indexed: 12/19/2022] Open
Abstract
Autophagy is essential for the maintenance of cellular homeostasis and its dysfunction has been linked to various diseases. Autophagy is a membrane driven process and tightly regulated by membrane-associated proteins. Here, we summarized membrane lipid composition, and membrane-associated proteins relevant to autophagy from a spatiotemporal perspective. In particular, we focused on three important membrane remodeling processes in autophagy, lipid transfer for phagophore elongation, membrane scission for phagophore closure, and autophagosome-lysosome membrane fusion. We discussed the significance of the discoveries in this field and possible avenues to follow for future studies. Finally, we summarized the membrane-associated biochemical techniques and assays used to study membrane properties, with a discussion of their applications in autophagy.
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Affiliation(s)
- Linsen Li
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Feed Industry Centre, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Mindan Tong
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Yuhui Fu
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Fang Chen
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Shen Zhang
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Hanmo Chen
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Xi Ma
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Feed Industry Centre, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Defa Li
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Feed Industry Centre, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China.
| | - Xiaoxia Liu
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Qing Zhong
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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24
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Abstract
Exosomes are nanoscale extracellular vesicles that can transport cargos of proteins, lipids, DNA, various RNA species and microRNAs (miRNAs). Exosomes can enter cells and deliver their contents to recipient cell. Owing to their cargo exosomes can transfer different molecules to the target cells and change the phenotype of these cells. The fate of the contents of an exosome depends on its target destination. Various mechanisms for exosome uptake by target cells have been proposed, but the mechanisms responsible for exosomes internalization into cells are still debated. Exosomes exposed cells produce labeled protein kinases, which are expressed by other cells. This means that these kinases are internalized by exosomes, and transported into the cytoplasm of recipient cells. Many studies have confirmed that exosomes are not only secreted by living cells, but also internalized or accumulated by the other cells. The "next cell hypothesis" supports the notion that exosomes constitute communication vehicles between neighboring cells. By this mechanism, exosomes participate in the development of diabetes and its associated complications, critically contribute to the spreading of neuronal damage in Alzheimer's disease, and non-proteolysed form of Fas ligand (mFasL)-bearing exosomes trigger the apoptosis of T lymphocytes. Furthermore, exosomes derived from human B lymphocytes induce antigen-specific major histocompatibility complex (MHC) class II-restricted T cell responses. Interestingly, exosomes secreted by cancer cells have been demonstrated to express tumor antigens, as well as immune suppressive molecules. This process is defined as "exosome-immune suppression" concept. The interplay via the exchange of exosomes between cancer cells and between cancer cells and the tumor stroma promote the transfer of oncogenes and onco-miRNAs from one cell to other. Circulating exosomes that are released from hypertrophic adipocytes are effective in obesity-related complications. On the other hand, the "inflammasome-induced" exosomes can activate inflammatory responses in recipient cells. In this chapter protein kinases-related checkpoints are emphasized considering the regulation of exosome biogenesis, secretory traffic, and their impacts on cell death, tumor growth, immune system, and obesity.
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Affiliation(s)
- Atilla Engin
- Department of General Surgery, Faculty of Medicine, Gazi University, Ankara, Turkey.
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25
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Montaño-Rendón F, Grinstein S, Walpole GFW. Monitoring Phosphoinositide Fluxes and Effectors During Leukocyte Chemotaxis and Phagocytosis. Front Cell Dev Biol 2021; 9:626136. [PMID: 33614656 PMCID: PMC7890364 DOI: 10.3389/fcell.2021.626136] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/06/2021] [Indexed: 01/22/2023] Open
Abstract
The dynamic re-organization of cellular membranes in response to extracellular stimuli is fundamental to the cell physiology of myeloid and lymphoid cells of the immune system. In addition to maintaining cellular homeostatic functions, remodeling of the plasmalemma and endomembranes endow leukocytes with the potential to relay extracellular signals across their biological membranes to promote rolling adhesion and diapedesis, migration into the tissue parenchyma, and to ingest foreign particles and effete cells. Phosphoinositides, signaling lipids that control the interface of biological membranes with the external environment, are pivotal to this wealth of functions. Here, we highlight the complex metabolic transitions that occur to phosphoinositides during several stages of the leukocyte lifecycle, namely diapedesis, migration, and phagocytosis. We describe classical and recently developed tools that have aided our understanding of these complex lipids. Finally, major downstream effectors of inositides are highlighted including the cytoskeleton, emphasizing the importance of these rare lipids in immunity and disease.
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Affiliation(s)
- Fernando Montaño-Rendón
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada
| | - Glenn F W Walpole
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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26
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Hirst J, Hesketh GG, Gingras AC, Robinson MS. Rag GTPases and phosphatidylinositol 3-phosphate mediate recruitment of the AP-5/SPG11/SPG15 complex. J Cell Biol 2021; 220:211690. [PMID: 33464297 PMCID: PMC7814351 DOI: 10.1083/jcb.202002075] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 05/21/2020] [Accepted: 12/02/2020] [Indexed: 12/31/2022] Open
Abstract
Adaptor protein complex 5 (AP-5) and its partners, SPG11 and SPG15, are recruited onto late endosomes and lysosomes. Here we show that recruitment of AP-5/SPG11/SPG15 is enhanced in starved cells and occurs by coincidence detection, requiring both phosphatidylinositol 3-phosphate (PI3P) and Rag GTPases. PI3P binding is via the SPG15 FYVE domain, which, on its own, localizes to early endosomes. GDP-locked RagC promotes recruitment of AP-5/SPG11/SPG15, while GTP-locked RagA prevents its recruitment. Our results uncover an interplay between AP-5/SPG11/SPG15 and the mTORC1 pathway and help to explain the phenotype of AP-5/SPG11/SPG15 deficiency in patients, including the defect in autophagic lysosome reformation.
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Affiliation(s)
- Jennifer Hirst
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK,Jennifer Hirst:
| | - Geoffrey G. Hesketh
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Margaret S. Robinson
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK,Correspondence to Margaret S. Robinson:
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27
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Kamal MM, Ishikawa S, Takahashi F, Suzuki K, Kamo M, Umezawa T, Shinozaki K, Kawamura Y, Uemura M. Large-Scale Phosphoproteomic Study of Arabidopsis Membrane Proteins Reveals Early Signaling Events in Response to Cold. Int J Mol Sci 2020; 21:E8631. [PMID: 33207747 PMCID: PMC7696906 DOI: 10.3390/ijms21228631] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/22/2022] Open
Abstract
Cold stress is one of the major factors limiting global crop production. For survival at low temperatures, plants need to sense temperature changes in the surrounding environment. How plants sense and respond to the earliest drop in temperature is still not clearly understood. The plasma membrane and its adjacent extracellular and cytoplasmic sites are the first checkpoints for sensing temperature changes and the subsequent events, such as signal generation and solute transport. To understand how plants respond to early cold exposure, we used a mass spectrometry-based phosphoproteomic method to study the temporal changes in protein phosphorylation events in Arabidopsis membranes during 5 to 60 min of cold exposure. The results revealed that brief cold exposures led to rapid phosphorylation changes in the proteins involved in cellular ion homeostasis, solute and protein transport, cytoskeleton organization, vesical trafficking, protein modification, and signal transduction processes. The phosphorylation motif and kinase-substrate network analysis also revealed that multiple protein kinases, including RLKs, MAPKs, CDPKs, and their substrates, could be involved in early cold signaling. Taken together, our results provide a first look at the cold-responsive phosphoproteome changes of Arabidopsis membrane proteins that can be a significant resource to understand how plants respond to an early temperature drop.
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Affiliation(s)
- Md Mostafa Kamal
- United Graduate School of Agricultural Sciences, Iwate University, Morioka 020-8550, Japan; (M.M.K.); (Y.K.)
| | - Shinnosuke Ishikawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei 184-8588, Japan; (S.I.); (T.U.)
| | - Fuminori Takahashi
- Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, 3-1-1 Koyadai, Tsukuba 305-0074, Japan; (F.T.); (K.S.)
| | - Ko Suzuki
- Department of Biochemistry, Iwate Medical University, Yahaba 028-3694, Japan; (K.S.); (M.K.)
| | - Masaharu Kamo
- Department of Biochemistry, Iwate Medical University, Yahaba 028-3694, Japan; (K.S.); (M.K.)
| | - Taishi Umezawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei 184-8588, Japan; (S.I.); (T.U.)
| | - Kazuo Shinozaki
- Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, 3-1-1 Koyadai, Tsukuba 305-0074, Japan; (F.T.); (K.S.)
| | - Yukio Kawamura
- United Graduate School of Agricultural Sciences, Iwate University, Morioka 020-8550, Japan; (M.M.K.); (Y.K.)
- Department of Plant-Bioscience, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan
| | - Matsuo Uemura
- United Graduate School of Agricultural Sciences, Iwate University, Morioka 020-8550, Japan; (M.M.K.); (Y.K.)
- Department of Plant-Bioscience, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan
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28
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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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29
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Darios F, Stevanin G. Impairment of Lysosome Function and Autophagy in Rare Neurodegenerative Diseases. J Mol Biol 2020; 432:2714-2734. [PMID: 32145221 PMCID: PMC7232018 DOI: 10.1016/j.jmb.2020.02.033] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/28/2020] [Accepted: 02/28/2020] [Indexed: 02/07/2023]
Abstract
Rare genetic diseases affect a limited number of patients, but their etiology is often known, facilitating the development of reliable animal models and giving the opportunity to investigate physiopathology. Lysosomal storage disorders are a group of rare diseases due to primary alteration of lysosome function. These diseases are often associated with neurological symptoms, which highlighted the importance of lysosome in neurodegeneration. Likewise, other groups of rare neurodegenerative diseases also present lysosomal alteration. Lysosomes fuse with autophagosomes and endosomes to allow the degradation of their content thanks to hydrolytic enzymes. It has emerged that alteration of the autophagy–lysosome pathway could play a critical role in neuronal death in many neurodegenerative diseases. Using a repertoire of selected rare neurodegenerative diseases, we highlight that a variety of alterations of the autophagy–lysosome pathway are associated with neuronal death. Yet, in most cases, it is still unclear why alteration of this pathway can lead to neurodegeneration. Lysosome function is impaired in many rare neurodegenerative diseases, making it a convergent point for these diseases. Impaired lysosome function is associated with alteration of the autophagy pathway. Autophagy–lysosome pathway can be impaired at various steps in different rare neurodegenerative diseases. The mechanisms linking impaired autophagy–lysosome pathway to neurodegeneration are still not fully elucidated.
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Affiliation(s)
- Frédéric Darios
- Sorbonne Université, F-75013, Paris, France; Inserm, U1127, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Institut du Cerveau et de la Moelle Epinière, ICM, F-75013 Paris, France.
| | - Giovanni Stevanin
- Sorbonne Université, F-75013, Paris, France; Inserm, U1127, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Institut du Cerveau et de la Moelle Epinière, ICM, F-75013 Paris, France; PSL Research University, Ecole Pratique des Hautes Etudes, Laboratoire de Neurogénétique, F-75013 Paris, France
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30
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Cernikova L, Faso C, Hehl AB. Phosphoinositide-binding proteins mark, shape and functionally modulate highly-diverged endocytic compartments in the parasitic protist Giardia lamblia. PLoS Pathog 2020; 16:e1008317. [PMID: 32092130 PMCID: PMC7058353 DOI: 10.1371/journal.ppat.1008317] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 03/05/2020] [Accepted: 01/14/2020] [Indexed: 12/18/2022] Open
Abstract
Phosphorylated derivatives of phosphatidylinositol (PIPs) are key membrane lipid residues involved in clathrin-mediated endocytosis (CME). CME relies on PIP species PI(4,5)P2 to mark endocytic sites at the plasma membrane (PM) associated to clathrin-coated vesicle (CCV) formation. The highly diverged parasitic protist Giardia lamblia presents disordered and static clathrin assemblies at PM invaginations, contacting specialized endocytic organelles called peripheral vacuoles (PVs). The role for clathrin assemblies in fluid phase uptake and their link to internal membranes via PIP-binding adaptors is unknown. Here we provide evidence for a robust link between clathrin assemblies and fluid-phase uptake in G. lamblia mediated by proteins carrying predicted PX, FYVE and NECAP1 PIP-binding modules. We show that chemical and genetic perturbation of PIP-residue binding and turnover elicits novel uptake and organelle-morphology phenotypes. A combination of co-immunoprecipitation and in silico analysis techniques expands the initial PIP-binding network with addition of new members. Our data indicate that, despite the partial conservation of lipid markers and protein cohorts known to play important roles in dynamic endocytic events in well-characterized model systems, the Giardia lineage presents a strikingly divergent clathrin-centered network. This includes several PIP-binding modules, often associated to domains of currently unknown function that shape and modulate fluid-phase uptake at PVs. In well-characterized model eukaryotes, clathrin-mediated endocytosis is a key process for uptake of extracellular material and is regulated by more than 50 known proteins. A large number of these carry phosphoinositide (PIP)-binding domains and play a central role in the regulation of endocytosis. Here, we report on the detailed functional characterization of PIP-binding proteins in the intestinal parasitic protist Giardia lamblia. We show evidence that proteins carrying specific PIP-binding domains are directly involved in fluid-phase uptake. Furthermore, using co-immunoprecipitation assays, we confirm these proteins’ association to G. lamblia’s clathrin assemblies. In addition, using state-of-the-art imaging strategies, we demonstrate a previously unappreciated level of complexity involving PIPs and their partner proteins in marking and shaping G. lamblia’s unique endocytic compartments. Our data contribute substantially to an updated working model for G. lamblia’s host-parasite interface, demonstrating how uptake in this parasite is directly regulated by a variety of PIP residues and PIP-binding modules, which have been re-routed from conserved pathways, likely as a result of host-parasite co-evolution.
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Affiliation(s)
- Lenka Cernikova
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Carmen Faso
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
- Institute of Cell Biology, University of Bern, Bern, Switzerland
- * E-mail: (CF); (AH)
| | - Adrian B. Hehl
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
- * E-mail: (CF); (AH)
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31
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Vasanthakumar T, Rubinstein JL. Structure and Roles of V-type ATPases. Trends Biochem Sci 2020; 45:295-307. [PMID: 32001091 DOI: 10.1016/j.tibs.2019.12.007] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/05/2019] [Accepted: 12/31/2019] [Indexed: 12/19/2022]
Abstract
V-ATPases are membrane-embedded protein complexes that function as ATP hydrolysis-driven proton pumps. V-ATPases are the primary source of organellar acidification in all eukaryotes, making them essential for many fundamental cellular processes. Enzymatic activity can be modulated by regulated and reversible disassembly of the complex, and several subunits of mammalian V-ATPase have multiple isoforms that are differentially localized. Although the biochemical properties of the different isoforms are currently unknown, mutations in specific subunit isoforms have been associated with various diseases, making V-ATPases potential drug targets. V-ATPase structure and activity have been best characterized in Saccharomyces cerevisiae, where recent structures have revealed details about the dynamics of the enzyme, the proton translocation pathway, and conformational changes associated with regulated disassembly and autoinhibition.
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Affiliation(s)
- Thamiya Vasanthakumar
- The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - John L Rubinstein
- The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medical Biophysics, The University of Toronto, Toronto, ON M5G 1L7, Canada.
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32
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Skotland T, Sagini K, Sandvig K, Llorente A. An emerging focus on lipids in extracellular vesicles. Adv Drug Deliv Rev 2020; 159:308-321. [PMID: 32151658 DOI: 10.1016/j.addr.2020.03.002] [Citation(s) in RCA: 272] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/02/2020] [Accepted: 03/05/2020] [Indexed: 02/07/2023]
Abstract
Extracellular vesicles contain a lipid bilayer membrane that protects the encapsulated material, such as proteins, nucleic acids, lipids and metabolites, from the extracellular environment. These vesicles are released from cells via different mechanisms. During recent years extracellular vesicles have been studied as possible biomarkers for different diseases, as biological nanoparticles for drug delivery, and in basic studies as a tool to understand the structure of biological membranes and the mechanisms involved in vesicular trafficking. Lipids are essential molecular components of extracellular vesicles, but at the moment our knowledge about the lipid composition and the function of lipids in these vesicles is limited. However, the interest of the research community in these molecules is increasing as their role in extracellular vesicles is starting to be acknowledged. In this review, we will present the status of the field and describe what is needed to bring it forward.
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Affiliation(s)
- Tore Skotland
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway
| | - Krizia Sagini
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway
| | - Kirsten Sandvig
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway; Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Alicia Llorente
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway.
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33
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Severe Consequences of SAC3/FIG4 Phosphatase Deficiency to Phosphoinositides in Patients with Charcot-Marie-Tooth Disease Type-4J. Mol Neurobiol 2019; 56:8656-8667. [PMID: 31313076 DOI: 10.1007/s12035-019-01693-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/01/2019] [Indexed: 01/26/2023]
Abstract
Charcot-Marie-Tooth disease type-4J (CMT4J), an autosomal recessively inherited peripheral neuropathy characterized by neuronal degeneration, segmental demyelination, and limb muscle weakness, is caused by compound heterozygous mutations in the SAC3/FIG4 gene, resulting in SAC3/FIG4 protein deficiency. SAC3/FIG4 is a phosphatase that not only turns over PtdIns(3,5)P2 to PtdIns3P but also promotes PtdIns(3,5)P2 synthesis by activating the PIKFYVE kinase that also makes PtdIns5P. Whether CMT4J patients have alterations in PtdIns(3,5)P2, PtdIns5P or in other phosphoinositides (PIs), and if yes, in what direction these changes might be, has never been examined. We performed PI profiling in primary fibroblasts from a cohort of CMT4J patients. Subsequent to myo-[2-3H]inositol cell labeling to equilibrium, steady-state levels of PIs were quantified by HPLC under conditions concurrently detecting PtdIns5P, PtdIns(3,5)P2, and the other PIs. Immunoblotting verified SAC3/FIG4 depletion in CMT4J fibroblasts. Compared to normal human controls (n = 9), both PtdIns(3,5)P2 and PtdIns5P levels were significantly decreased in CMT4J fibroblasts (n = 13) by 36.4 ± 3.6% and 43.1 ± 4.4%, respectively (p < 0.0001). These reductions were independent of patients' gender or disease onset. Although mean values for PtdIns3P in the CMT4J cohort remained unchanged, there were high variations in PtdIns3P among individual patients. Aberrant endolysosomal vacuoles, typically seen under PtdIns(3,5)P2 reduction, were apparent but not in fibroblasts from all patients. The subset of patients without aberrant vacuoles exhibited especially low PtdIns3P levels. Concomitant decreases in PtdIns5P and PtdIns(3,5)P2 and the link between PtdIns3P levels and cellular vacuolization are novel insights shedding further light into the molecular determinants in CMT4J polyneuropathy.
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Rahmani S, Defferrari MS, Wakarchuk WW, Antonescu CN. Energetic adaptations: Metabolic control of endocytic membrane traffic. Traffic 2019; 20:912-931. [DOI: 10.1111/tra.12705] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 09/11/2019] [Accepted: 10/13/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Sadia Rahmani
- Department of Chemistry and BiologyRyerson University Toronto Ontario Canada
| | | | - Warren W. Wakarchuk
- Department of Chemistry and BiologyRyerson University Toronto Ontario Canada
- Department of Biological SciencesUniversity of Alberta Edmonton Alberta Canada
| | - Costin N. Antonescu
- Department of Chemistry and BiologyRyerson University Toronto Ontario Canada
- Keenan Research Centre for Biomedical Science of St. Michael's Hospital Toronto Ontario Canada
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Essential Role for the Phosphatidylinositol 3,5-Bisphosphate Synthesis Complex in Caspofungin Tolerance and Virulence in Candida glabrata. Antimicrob Agents Chemother 2019; 63:AAC.00886-19. [PMID: 31138567 PMCID: PMC6658794 DOI: 10.1128/aac.00886-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 05/21/2019] [Indexed: 11/25/2022] Open
Abstract
Increasing resistance of the human opportunistic fungal pathogen Candida glabrata toward the echinocandin antifungals, which target the cell wall, is a matter of grave clinical concern. Echinocandin resistance in C. glabrata has primarily been associated with mutations in the β-glucan synthase-encoding genes C. glabrataFKS1 (CgFKS1) and CgFKS2. This notwithstanding, the role of the phosphoinositide signaling in antifungal resistance is just beginning to be deciphered. Increasing resistance of the human opportunistic fungal pathogen Candida glabrata toward the echinocandin antifungals, which target the cell wall, is a matter of grave clinical concern. Echinocandin resistance in C. glabrata has primarily been associated with mutations in the β-glucan synthase-encoding genes C. glabrataFKS1 (CgFKS1) and CgFKS2. This notwithstanding, the role of the phosphoinositide signaling in antifungal resistance is just beginning to be deciphered. The phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] is a low-abundance lipid molecule that is pivotal to the intracellular membrane traffic. Here, we demonstrate for the first time that the PI(3,5)P2 kinase CgFab1, along with its activity regulator CgVac7 and the scaffolding protein CgVac14, is required for maintenance of the cell wall chitin content, survival of the cell wall, and caspofungin stress. Further, deletion analyses implicated the PI(3,5)P2 phosphatase CgFig4 in the regulation of PI(3,5)P2 levels and azole and echinocandin tolerance through CgVac14. We also show the localization of the CgFab1 lipid kinase to the vacuole to be independent of the CgVac7, CgVac14, and CgFig4 proteins. Lastly, our data demonstrate an essential requirement for PI(3,5)P2 signaling components, CgFab1, CgVac7, and CgVac14, in the intracellular survival and virulence in C. glabrata. Altogether, our data have yielded key insights into the functions and metabolism of PI(3,5)P2 lipid in the pathogenic yeast C. glabrata. In addition, our data highlight that CgVac7, whose homologs are absent in higher eukaryotes, may represent a promising target for antifungal therapy.
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Sharma G, Guardia CM, Roy A, Vassilev A, Saric A, Griner LN, Marugan J, Ferrer M, Bonifacino JS, DePamphilis ML. A family of PIKFYVE inhibitors with therapeutic potential against autophagy-dependent cancer cells disrupt multiple events in lysosome homeostasis. Autophagy 2019; 15:1694-1718. [PMID: 30806145 DOI: 10.1080/15548627.2019.1586257] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
High-throughput screening identified 5 chemical analogs (termed the WX8-family) that disrupted 3 events in lysosome homeostasis: (1) lysosome fission via tubulation without preventing homotypic lysosome fusion; (2) trafficking of molecules into lysosomes without altering lysosomal acidity, and (3) heterotypic fusion between lysosomes and autophagosomes. Remarkably, these compounds did not prevent homotypic fusion between lysosomes, despite the fact that homotypic fusion required some of the same machinery essential for heterotypic fusion. These effects varied 400-fold among WX8-family members, were time and concentration dependent, reversible, and resulted primarily from their ability to bind specifically to the PIKFYVE phosphoinositide kinase. The ability of the WX8-family to prevent lysosomes from participating in macroautophagy/autophagy suggested they have therapeutic potential in treating autophagy-dependent diseases. In fact, the most potent family member (WX8) was 100-times more lethal to 'autophagy-addicted' melanoma A375 cells than the lysosomal inhibitors hydroxychloroquine and chloroquine. In contrast, cells that were insensitive to hydroxychloroquine and chloroquine were also insensitive to WX8. Therefore, the WX8-family of PIKFYVE inhibitors provides a basis for developing drugs that could selectively kill autophagy-dependent cancer cells, as well as increasing the effectiveness of established anti-cancer therapies through combinatorial treatments. Abbreviations: ACTB: actin beta; Baf: bafilomycin A1; BECN1: beclin 1; BODIPY: boron-dipyrromethene; BORC: BLOC-1 related complex; BRAF: B-Raf proto-oncogene, serine/threonine kinase; BSA: bovine serum albumin; CTSD: cathepsin D; CQ: chloroquine; DNA: deoxyribonucleic acid; EC50: half maximal effective concentration; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; HCQ: hydroxychloroquine; HOPS complex: homotypic fusion and protein sorting complex; Kd: equilibrium binding constant; IC50: half maximal inhibitory concentration; KO: knockout; LAMP1: lysosomal associated membrane protein 1; MAP1LC3A: microtubule associated protein 1 light chain 3 alpha; MES: 2-(N-morpholino)ethanesulphonic acid; MTOR: mechanistic target of rapamycin kinase; μM: micromolar; NDF: 3-methylbenzaldehyde (2,6-dimorpholin-4-ylpyrimidin-4-yl)hydrazine;NEM: N-ethylmaleimide; NSF: N-ethylmaleimide sensitive factor; PBS: phosphate-buffered saline; PIKFYVE: phosphoinositide kinase, FYVE-type zinc finger containing; PIP4K2C: phosphatidylinositol-5-phosphate 4-kinase type 2 gamma; PtdIns3P: phosphatidylinositol 3-phosphate; PtdIns(3,5)P2: phosphatidylinositol 3,5-biphosphate; RFP: red fluorescent protein; RPS6: ribosomal protein S6; RPS6KB1: ribosomal protein S6 kinase B1; SQSTM1: sequestosome 1; TWEEN 20: polysorbate 20; V-ATPase: vacuolar-type H+-translocating ATPase; VPS39: VPS39 subunit of HOPS complex; VPS41: VPS41 subunit of HOPS complex; WWL: benzaldehyde [2,6-di(4-morpholinyl)-4-pyrimidinyl]hydrazone; WX8: 1H-indole-3-carbaldehyde [4-anilino-6-(4-morpholinyl)-1,3,5-triazin-2-yl]hydrazine; XBA: N-(3-chloro-4-fluorophenyl)-4,6-dimorpholino-1,3,5-triazin-2-amine hydrochloride; XB6: N-(4-ethylphenyl)-4,6-dimorpholino-1,3,5-triazin-2-amine hydrochloride.
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Affiliation(s)
- Gaurav Sharma
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Carlos M Guardia
- Cell Biology and Neurobiology Branch, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Ajit Roy
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Alex Vassilev
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Amra Saric
- Cell Biology and Neurobiology Branch, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Lori N Griner
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Juan Marugan
- Division of Pre-Clinical Innovation, NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health , Rockville , MD , USA
| | - Marc Ferrer
- Division of Pre-Clinical Innovation, NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health , Rockville , MD , USA
| | - Juan S Bonifacino
- Cell Biology and Neurobiology Branch, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Melvin L DePamphilis
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
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Buckley CM, Heath VL, Guého A, Bosmani C, Knobloch P, Sikakana P, Personnic N, Dove SK, Michell RH, Meier R, Hilbi H, Soldati T, Insall RH, King JS. PIKfyve/Fab1 is required for efficient V-ATPase and hydrolase delivery to phagosomes, phagosomal killing, and restriction of Legionella infection. PLoS Pathog 2019; 15:e1007551. [PMID: 30730983 PMCID: PMC6382210 DOI: 10.1371/journal.ppat.1007551] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 02/20/2019] [Accepted: 01/03/2019] [Indexed: 12/11/2022] Open
Abstract
By engulfing potentially harmful microbes, professional phagocytes are continually at risk from intracellular pathogens. To avoid becoming infected, the host must kill pathogens in the phagosome before they can escape or establish a survival niche. Here, we analyse the role of the phosphoinositide (PI) 5-kinase PIKfyve in phagosome maturation and killing, using the amoeba and model phagocyte Dictyostelium discoideum. PIKfyve plays important but poorly understood roles in vesicular trafficking by catalysing formation of the lipids phosphatidylinositol (3,5)-bisphosphate (PI(3,5)2) and phosphatidylinositol-5-phosphate (PI(5)P). Here we show that its activity is essential during early phagosome maturation in Dictyostelium. Disruption of PIKfyve inhibited delivery of both the vacuolar V-ATPase and proteases, dramatically reducing the ability of cells to acidify newly formed phagosomes and digest their contents. Consequently, PIKfyve- cells were unable to generate an effective antimicrobial environment and efficiently kill captured bacteria. Moreover, we demonstrate that cells lacking PIKfyve are more susceptible to infection by the intracellular pathogen Legionella pneumophila. We conclude that PIKfyve-catalysed phosphoinositide production plays a crucial and general role in ensuring early phagosomal maturation, protecting host cells from diverse pathogenic microbes.
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Affiliation(s)
- Catherine M. Buckley
- Centre for Membrane Interactions and Dynamics, Department of Biomedical Sciences, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Bateson Centre, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Victoria L. Heath
- Institute of Cardiovascular Sciences, Institute for Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Aurélie Guého
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Cristina Bosmani
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Paulina Knobloch
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Phumzile Sikakana
- Centre for Membrane Interactions and Dynamics, Department of Biomedical Sciences, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Nicolas Personnic
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Stephen K. Dove
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Robert H. Michell
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Roger Meier
- Institute of Molecular Life Sciences, University of Zürich, Zürich, Switzerland
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Thierry Soldati
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Robert H. Insall
- CRUK Beatson Institute, Switchback Road, Bearsden, Glasgow, United Kingdom
| | - Jason S. King
- Centre for Membrane Interactions and Dynamics, Department of Biomedical Sciences, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Bateson Centre, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
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Baranov MV, Bianchi F, Schirmacher A, van Aart MAC, Maassen S, Muntjewerff EM, Dingjan I, Ter Beest M, Verdoes M, Keyser SGL, Bertozzi CR, Diederichsen U, van den Bogaart G. The Phosphoinositide Kinase PIKfyve Promotes Cathepsin-S-Mediated Major Histocompatibility Complex Class II Antigen Presentation. iScience 2018; 11:160-177. [PMID: 30612035 PMCID: PMC6319320 DOI: 10.1016/j.isci.2018.12.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 11/28/2018] [Accepted: 12/14/2018] [Indexed: 02/07/2023] Open
Abstract
Antigen presentation to T cells in major histocompatibility complex class II (MHC class II) requires the conversion of early endo/phagosomes into lysosomes by a process called maturation. Maturation is driven by the phosphoinositide kinase PIKfyve. Blocking PIKfyve activity by small molecule inhibitors caused a delay in the conversion of phagosomes into lysosomes and in phagosomal acidification, whereas production of reactive oxygen species (ROS) increased. Elevated ROS resulted in reduced activity of cathepsin S and B, but not X, causing a proteolytic defect of MHC class II chaperone invariant chain Ii processing. We developed a novel universal MHC class II presentation assay based on a bio-orthogonal "clickable" antigen and showed that MHC class II presentation was disrupted by the inhibition of PIKfyve, which in turn resulted in reduced activation of CD4+ T cells. Our results demonstrate a key role of PIKfyve in the processing and presentation of antigens, which should be taken into consideration when targeting PIKfyve in autoimmune disease and cancer.
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Affiliation(s)
- Maksim V Baranov
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Frans Bianchi
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands; Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, Groningen 9747 AG, the Netherlands
| | - Anastasiya Schirmacher
- Institute of Organic and Biomolecular Chemistry, Georg-August-University of Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Melissa A C van Aart
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Sjors Maassen
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands; Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, Groningen 9747 AG, the Netherlands
| | - Elke M Muntjewerff
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Ilse Dingjan
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Martin Ter Beest
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Martijn Verdoes
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | | | - Carolyn R Bertozzi
- Department of Chemistry and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Ulf Diederichsen
- Institute of Organic and Biomolecular Chemistry, Georg-August-University of Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Geert van den Bogaart
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands; Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, Groningen 9747 AG, the Netherlands.
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Isobe Y, Nigorikawa K, Tsurumi G, Takemasu S, Takasuga S, Kofuji S, Hazeki K. PIKfyve accelerates phagosome acidification through activation of TRPML1 while arrests aberrant vacuolation independent of the Ca2+ channel. J Biochem 2018; 165:75-84. [DOI: 10.1093/jb/mvy084] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/05/2018] [Indexed: 01/17/2023] Open
Affiliation(s)
- Yuri Isobe
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Minamiku Kasumi 1-2-3, Hiroshima, Japan
| | - Kiyomi Nigorikawa
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Minamiku Kasumi 1-2-3, Hiroshima, Japan
| | - Go Tsurumi
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Minamiku Kasumi 1-2-3, Hiroshima, Japan
| | - Shinya Takemasu
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Minamiku Kasumi 1-2-3, Hiroshima, Japan
| | - Shunsuke Takasuga
- Department of Pathology and Immunology, Akita University School of Medicine, Akita, Japan
| | - Satoshi Kofuji
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Minamiku Kasumi 1-2-3, Hiroshima, Japan
| | - Kaoru Hazeki
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Minamiku Kasumi 1-2-3, Hiroshima, Japan
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40
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Sbrissa D, Naisan G, Ikonomov OC, Shisheva A. Apilimod, a candidate anticancer therapeutic, arrests not only PtdIns(3,5)P2 but also PtdIns5P synthesis by PIKfyve and induces bafilomycin A1-reversible aberrant endomembrane dilation. PLoS One 2018; 13:e0204532. [PMID: 30240452 PMCID: PMC6150535 DOI: 10.1371/journal.pone.0204532] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 09/10/2018] [Indexed: 01/02/2023] Open
Abstract
PIKfyve, an evolutionarily conserved kinase synthesizing PtdIns5P and PtdIns(3,5)P2, is crucial for mammalian cell proliferation and viability. Accordingly, PIKfyve inhibitors are now in clinical trials as anti-cancer drugs. Among those, apilimod is the most promising, yet its potency to inhibit PIKfyve and affect endomembrane homeostasis is only partially characterized. We demonstrate here for the first time that apilimod powerfully inhibited in vitro synthesis of PtdIns5P along with that of PtdIns(3,5)P2. HPLC-based resolution of intracellular phosphoinositides (PIs) revealed that apilimod triggered a marked reduction of both lipids in the context of intact cells. Notably, there was also a profound rise in PtdIns3P resulting from arrested PtdIns3P consumption for PtdIns(3,5)P2 synthesis. As typical for PIKfyve inhibition and the concomitant PtdIns(3,5)P2 reduction, apilimod induced the appearance of dilated endomembrane structures in the form of large translucent cytoplasmic vacuoles. Remarkably, bafilomycin A1 (BafA1) fully reversed the aberrant cell phenotype back to normal and completely precluded the appearance of cytoplasmic vacuoles when added prior to apilimod. Inspection of the PI profiles ruled out restoration of the reduced PtdIns(3,5)P2 pool as a molecular mechanism underlying BafA1 rescue. Rather, we found that BafA1 markedly attenuated the PtdIns3P elevation under PIKfyve inhibition. This was accompanied by profoundly decreased endosomal recruitment of fusogenic EEA1. Together, our data demonstrate that apilimod inhibits not only PtdIns(3,5)P2 but also PtdIns5P synthesis and that the cytoplasmic vacuolization triggered by the inhibitor is precluded or reversed by BafA1 through a mechanism associated, in part, with reduction in both PtdIns3P levels and EEA1 membrane recruitment.
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Affiliation(s)
- Diego Sbrissa
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Ghassan Naisan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Ognian C. Ikonomov
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- * E-mail:
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41
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McGough IJ, de Groot REA, Jellett AP, Betist MC, Varandas KC, Danson CM, Heesom KJ, Korswagen HC, Cullen PJ. SNX3-retromer requires an evolutionary conserved MON2:DOPEY2:ATP9A complex to mediate Wntless sorting and Wnt secretion. Nat Commun 2018; 9:3737. [PMID: 30213940 PMCID: PMC6137200 DOI: 10.1038/s41467-018-06114-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 08/13/2018] [Indexed: 12/28/2022] Open
Abstract
Wntless transports Wnt morphogens to the cell surface and is required for Wnt secretion and morphogenic gradients formation. Recycling of endocytosed Wntless requires the sorting nexin-3 (SNX3)-retromer-dependent endosome-to-Golgi transport pathway. Here we demonstrate the essential role of SNX3-retromer assembly for Wntless transport and report that SNX3 associates with an evolutionary conserved endosome-associated membrane re-modelling complex composed of MON2, DOPEY2 and the putative aminophospholipid translocase, ATP9A. In vivo suppression of Ce-mon-2, Ce-pad-1 or Ce-tat-5 (respective MON2, DOPEY2 and ATP9A orthologues) phenocopy a loss of SNX3-retromer function, leading to enhanced lysosomal degradation of Wntless and a Wnt phenotype. Perturbed Wnt signalling is also observed upon overexpression of an ATPase-inhibited TAT-5(E246Q) mutant, suggesting a role for phospholipid flippase activity during SNX3-retromer-mediated Wntless sorting. Together, these findings provide in vitro and in vivo mechanistic details to describe SNX3-retromer-mediated transport during Wnt secretion and the formation of Wnt-morphogenic gradients.
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Affiliation(s)
- Ian J McGough
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
- The Francis Crick Institute, 1 Midland Rd, London, NW1 1AT, UK
| | - Reinoud E A de Groot
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, Utrecht, 3584 CT, The Netherlands
| | - Adam P Jellett
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
| | - Marco C Betist
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, Utrecht, 3584 CT, The Netherlands
| | - Katherine C Varandas
- Program in Cell Biology, University of California, San Francisco, 16th Street, San Francisco, CA, 94158, USA
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA
| | - Chris M Danson
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
| | - Kate J Heesom
- Proteomics Facility, School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
| | - Hendrik C Korswagen
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, Utrecht, 3584 CT, The Netherlands.
| | - Peter J Cullen
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK.
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42
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Skotland T, Hessvik NP, Sandvig K, Llorente A. Exosomal lipid composition and the role of ether lipids and phosphoinositides in exosome biology. J Lipid Res 2018; 60:9-18. [PMID: 30076207 PMCID: PMC6314266 DOI: 10.1194/jlr.r084343] [Citation(s) in RCA: 403] [Impact Index Per Article: 67.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 07/24/2018] [Indexed: 12/11/2022] Open
Abstract
Exosomes are a type of extracellular vesicle released from cells after fusion of multivesicular bodies with the plasma membrane. These vesicles are often enriched in cholesterol, SM, glycosphingolipids, and phosphatidylserine. Lipids not only have a structural role in exosomal membranes but also are essential players in exosome formation and release to the extracellular environment. Our knowledge about the importance of lipids in exosome biology is increasing due to recent technological developments in lipidomics and a stronger focus on the biological functions of these molecules. Here, we review the available information about the lipid composition of exosomes. Special attention is given to ether lipids, a relatively unexplored type of lipids involved in membrane trafficking and abundant in some exosomes. Moreover, we discuss how the lipid composition of exosome preparations may provide useful information about their purity. Finally, we discuss the role of phosphoinositides, membrane phospholipids that help to regulate membrane dynamics, in exosome release and how this process may be linked to secretory autophagy. Knowledge about exosome lipid composition is important to understand the biology of these vesicles and to investigate possible medical applications.
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Affiliation(s)
- Tore Skotland
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-Norwegian Radium Hospital, 0379 Oslo, Norway
| | - Nina P Hessvik
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-Norwegian Radium Hospital, 0379 Oslo, Norway
| | - Kirsten Sandvig
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-Norwegian Radium Hospital, 0379 Oslo, Norway.,Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Alicia Llorente
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-Norwegian Radium Hospital, 0379 Oslo, Norway
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43
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Chintaluri K, Goulden BD, Celmenza C, Saffi G, Miraglia E, Hammond GRV, Botelho RJ. The PH domain from the Toxoplasma gondii PH-containing protein-1 (TgPH1) serves as an ectopic reporter of phosphatidylinositol 3-phosphate in mammalian cells. PLoS One 2018; 13:e0198454. [PMID: 29870544 PMCID: PMC5988325 DOI: 10.1371/journal.pone.0198454] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 05/18/2018] [Indexed: 12/29/2022] Open
Abstract
Phosphoinositide (PtdInsP) lipids recruit effector proteins to membranes to mediate a variety of functions including signal transduction and membrane trafficking. Each PtdInsP binds to a specific set of effectors through characteristic protein domains such as the PH, FYVE and PX domains. Domains with high affinity for a single PtdInsP species are useful as probes to visualize the distribution and dynamics of that PtdInsP. The endolysosomal system is governed by two primary PtdInsPs: phosphatidylinositol 3-phosphate [PtdIns(3)P] and phosphatidylinositol 3,5-bisphosphate [PtdIns(3,5)P2], which are thought to localize and control early endosomes and lysosomes/late endosomes, respectively. While PtdIns(3)P has been analysed with mammalian-derived PX and FYVE domains, PtdIns(3,5)P2 indicators remain controversial. Thus, complementary probes against these PtdInsPs are needed, including those originating from non-mammalian proteins. Here, we characterized in mammalian cells the dynamics of the PH domain from PH-containing protein-1 from the parasite Toxoplasma gondii (TgPH1), which was previously shown to bind PtdIns(3,5)P2 in vitro. However, we show that TgPH1 retains membrane-binding in PIKfyve-inhibited cells, suggesting that TgPH1 is not a viable PtdIns(3,5)P2 marker in mammalian cells. Instead, PtdIns(3)P depletion using pharmacological and enzyme-based assays dissociated TgPH1 from membranes. Indeed, TgPH1 co-localized with Rab5-positive early endosomes. In addition, TgPH1 co-localized and behaved similarly to the PX domain of p40phox and FYVE domain of EEA1, which are commonly used as PtdIns(3)P indicators. Collectively, TgPH1 offers a complementary reporter for PtdIns(3)P derived from a non-mammalian protein and that is distinct from commonly employed PX and FYVE domain-based probes.
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Affiliation(s)
- Krishna Chintaluri
- Department of Chemistry, Ryerson University, Toronto, Ontario, Canada
- The Molecular Science Graduate Program, Ryerson University, Toronto, Ontario, Canada
| | - Brady D. Goulden
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Camilyn Celmenza
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Golam Saffi
- Department of Chemistry, Ryerson University, Toronto, Ontario, Canada
- The Molecular Science Graduate Program, Ryerson University, Toronto, Ontario, Canada
| | - Emily Miraglia
- Department of Chemistry, Ryerson University, Toronto, Ontario, Canada
| | - Gerald R. V. Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
| | - Roberto J. Botelho
- Department of Chemistry, Ryerson University, Toronto, Ontario, Canada
- The Molecular Science Graduate Program, Ryerson University, Toronto, Ontario, Canada
- * E-mail:
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44
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Choy CH, Saffi G, Gray MA, Wallace C, Dayam RM, Ou ZYA, Lenk G, Puertollano R, Watkins SC, Botelho RJ. Lysosome enlargement during inhibition of the lipid kinase PIKfyve proceeds through lysosome coalescence. J Cell Sci 2018; 131:jcs.213587. [PMID: 29661845 DOI: 10.1242/jcs.213587] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 04/10/2018] [Indexed: 01/07/2023] Open
Abstract
Lysosomes receive and degrade cargo from endocytosis, phagocytosis and autophagy. They also play an important role in sensing and instructing cells on their metabolic state. The lipid kinase PIKfyve generates phosphatidylinositol-3,5-bisphosphate to modulate lysosome function. PIKfyve inhibition leads to impaired degradative capacity, ion dysregulation, abated autophagic flux and a massive enlargement of lysosomes. Collectively, this leads to various physiological defects, including embryonic lethality, neurodegeneration and overt inflammation. The reasons for such drastic lysosome enlargement remain unclear. Here, we examined whether biosynthesis and/or fusion-fission dynamics contribute to swelling. First, we show that PIKfyve inhibition activates TFEB, TFE3 and MITF, enhancing lysosome gene expression. However, this did not augment lysosomal protein levels during acute PIKfyve inhibition, and deletion of TFEB and/or related proteins did not impair lysosome swelling. Instead, PIKfyve inhibition led to fewer but enlarged lysosomes, suggesting that an imbalance favouring lysosome fusion over fission causes lysosome enlargement. Indeed, conditions that abated fusion curtailed lysosome swelling in PIKfyve-inhibited cells.
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Affiliation(s)
- Christopher H Choy
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada, M5B2K3.,The Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada, M5B2K3
| | - Golam Saffi
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada, M5B2K3.,The Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada, M5B2K3
| | - Matthew A Gray
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada, M5B2K3
| | - Callen Wallace
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Roya M Dayam
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada, M5B2K3.,The Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada, M5B2K3
| | - Zhen-Yi A Ou
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada, M5B2K3
| | - Guy Lenk
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rosa Puertollano
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Room 3537, Bethesda, MD 20892, USA
| | - Simon C Watkins
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Roberto J Botelho
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada, M5B2K3 .,The Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada, M5B2K3
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45
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Dirr ER, Ekhator OR, Blackwood R, Holden JG, Masliah E, Schultheis PJ, Fleming SM. Exacerbation of sensorimotor dysfunction in mice deficient in Atp13a2 and overexpressing human wildtype alpha-synuclein. Behav Brain Res 2018; 343:41-49. [PMID: 29407413 PMCID: PMC5829010 DOI: 10.1016/j.bbr.2018.01.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 01/17/2018] [Accepted: 01/22/2018] [Indexed: 12/26/2022]
Abstract
Loss of function mutations in the gene ATP13A2 are associated with Kufor-Rakeb Syndrome and Neuronal Ceroid Lipofuscinosis, the former designated as an inherited form of Parkinson's disease (PD). The function of ATP13A2 is unclear but in vitro studies indicate it is a lysosomal protein and may interact with the presynaptic protein alpha-synuclein (aSyn) and certain heavy metals. Accumulation of aSyn is a major component of lewy bodies, the pathological hallmark of PD. Atp13a2-deficient (13a2) mice develop age-dependent sensorimotor deficits, and accumulation of insoluble aSyn in the brain. To better understand the interaction between ATP13A2 and aSyn, double mutant mice with loss of Atp13a2 function combined with overexpression of human wildtype aSyn were generated. Female and male wildtype (WT), 13a2, aSyn, and 13a2-aSyn mice were tested on a battery of sensorimotor tests including adhesive removal, challenging beam traversal, spontaneous activity, gait, locomotor activity, and nest-building at 2, 4, and 6 months of age. Double mutant mice showed an earlier onset and accelerated alterations in sensorimotor function that were age, sex and test-dependent. Female 13a2-aSyn mice showed early and progressive dysfunction on the beam and in locomotor activity. In males, 13a2-aSyn mice showed more severe impairments in spontaneous activity and adhesive removal. Sex differences were also observed in aSyn and 13a2-aSyn mice on the beam, cylinder, and adhesive removal tests. In other tasks, double mutant mice displayed deficits similar to aSyn mice. These results indicate loss of Atp13a2 function exacerbates the sensorimotor phenotype in aSyn mice in an age and sex-dependent manner.
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Affiliation(s)
- Emily R Dirr
- Department of Neurology, School of Medicine, University of Cincinnati, USA
| | - Osunde R Ekhator
- Department of Neurology, School of Medicine, University of Cincinnati, USA
| | - Rachel Blackwood
- Department of Neurology, School of Medicine, University of Cincinnati, USA
| | - John G Holden
- Department of Neurology, School of Medicine, University of Cincinnati, USA
| | | | | | - Sheila M Fleming
- Department of Pharmaceutical Sciences and Center for Neurodegenerative Disease and Aging, Northeast Ohio Medical University, USA.
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46
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Narayanan P, Hütte M, Kudryasheva G, Taberner FJ, Lechner SG, Rehfeldt F, Gomez-Varela D, Schmidt M. Myotubularin related protein-2 and its phospholipid substrate PIP 2 control Piezo2-mediated mechanotransduction in peripheral sensory neurons. eLife 2018. [PMID: 29521261 PMCID: PMC5898911 DOI: 10.7554/elife.32346] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Piezo2 ion channels are critical determinants of the sense of light touch in vertebrates. Yet, their regulation is only incompletely understood. We recently identified myotubularin related protein-2 (Mtmr2), a phosphoinositide (PI) phosphatase, in the native Piezo2 interactome of murine dorsal root ganglia (DRG). Here, we demonstrate that Mtmr2 attenuates Piezo2-mediated rapidly adapting mechanically activated (RA-MA) currents. Interestingly, heterologous Piezo1 and other known MA current subtypes in DRG appeared largely unaffected by Mtmr2. Experiments with catalytically inactive Mtmr2, pharmacological blockers of PI(3,5)P2 synthesis, and osmotic stress suggest that Mtmr2-dependent Piezo2 inhibition involves depletion of PI(3,5)P2. Further, we identified a PI(3,5)P2 binding region in Piezo2, but not Piezo1, that confers sensitivity to Mtmr2 as indicated by functional analysis of a domain-swapped Piezo2 mutant. Altogether, our results propose local PI(3,5)P2 modulation via Mtmr2 in the vicinity of Piezo2 as a novel mechanism to dynamically control Piezo2-dependent mechanotransduction in peripheral sensory neurons. We often take our sense of touch for granted. Yet, our every-day life greatly depends on the ability to perceive our environment to alert us of danger or to further social interactions, such as mother-child bonding. Our sense of touch relies on the conversion of mechanical stimuli to electrical signals (this is known as mechanotransduction), which then travel to brain to be processed. This task is fulfilled by specific ion channels called Piezo2, which are activated when cells are exposed to pressure and other mechanical forces. These channels can be found in sensory nerves and specialized structures in the skin, where they help to detect physical contact, roughness of surfaces and the position of our body parts. It is still not clear how Piezo2 channels are regulated but previous research by several laboratories suggests that they work in conjunction with other proteins. One of these proteins is the myotubularin related protein-2, or Mtmr2 for short. Now, Narayanan et al. – including some of the researchers involved in the previous research – set out to advance our understanding of the molecular basis of touch and looked more closely at Mtmr2. To test if Mtmr2 played a role in mechanotransduction, Narayanan et al. both increased and reduced the levels of this protein in sensory neurons of mice grown in the laboratory. When Mtmr2 levels were low, the activity of Piezo2 channels increased. However, when the protein levels were high, Piezo2 channels were inhibited. These results suggest that Mtmr2 can control the activity of Piezo2. Further experiments, in which Mtmr2 was genetically modified or sensory neurons were treated with chemicals, revealed that Mtmr2 reduces a specific fatty acid in the membrane of nerve cells, which in turn attenuates the activity of Piezo2. This study identified Mtmr2 and distinct fatty acids in the cell membrane as new components of the complex setup required for the sense of touch. A next step will be to test if these molecules also influence the activity of Piezo2 when the skin has become injured or upon inflammation.
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Affiliation(s)
- Pratibha Narayanan
- Emmy Noether-Group Somatosensory Signaling and Systems Biology, Max Planck Institute for Experimental Medicine, Goettingen, Germany
| | - Meike Hütte
- Emmy Noether-Group Somatosensory Signaling and Systems Biology, Max Planck Institute for Experimental Medicine, Goettingen, Germany
| | - Galina Kudryasheva
- Third Institute of Physics - Biophysics, University of Goettingen, Goettingen, Germany
| | | | | | - Florian Rehfeldt
- Third Institute of Physics - Biophysics, University of Goettingen, Goettingen, Germany
| | - David Gomez-Varela
- Emmy Noether-Group Somatosensory Signaling and Systems Biology, Max Planck Institute for Experimental Medicine, Goettingen, Germany
| | - Manuela Schmidt
- Emmy Noether-Group Somatosensory Signaling and Systems Biology, Max Planck Institute for Experimental Medicine, Goettingen, Germany
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47
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Naufer A, Hipolito VEB, Ganesan S, Prashar A, Zaremberg V, Botelho RJ, Terebiznik MR. pH of endophagosomes controls association of their membranes with Vps34 and PtdIns(3)P levels. J Cell Biol 2017; 217:329-346. [PMID: 29089378 PMCID: PMC5748975 DOI: 10.1083/jcb.201702179] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 09/03/2017] [Accepted: 09/26/2017] [Indexed: 12/19/2022] Open
Abstract
Specific changes in phospholipid content are a hallmark of the membranes of maturing endosomes and phagosomes, but is it unclear how this is controlled. Naufer et al. now show that acidification of the lumen of endosomes and phagosomes triggers dissociation of the Vps34 lipid kinase from these organelles, which terminates PtdIns(3)P synthesis and signaling. Phagocytosis of filamentous bacteria occurs through tubular phagocytic cups (tPCs) and takes many minutes to engulf these filaments into phagosomes. Contravening the canonical phagocytic pathway, tPCs mature by fusing with endosomes. Using this model, we observed the sequential recruitment of early and late endolysosomal markers to the elongating tPCs. Surprisingly, the regulatory early endosomal lipid phosphatidylinositol-3-phosphate (PtdIns(3)P) persists on tPCs as long as their luminal pH remains neutral. Interestingly, by manipulating cellular pH, we determined that PtdIns(3)P behaves similarly in canonical phagosomes as well as endosomes. We found that this is the product of a pH-based mechanism that induces the dissociation of the Vps34 class III phosphatidylinositol-3-kinase from these organelles as they acidify. The detachment of Vps34 stops the production of PtdIns(3)P, allowing for the turnover of this lipid by PIKfyve. Given that PtdIns(3)P-dependent signaling is important for multiple cellular pathways, this mechanism for pH-dependent regulation of Vps34 could be at the center of many PtdIns(3)P-dependent cellular processes.
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Affiliation(s)
- Amriya Naufer
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Canada.,Department of Cell and System Biology, University of Toronto Scarborough, Toronto, Canada
| | - Victoria E B Hipolito
- Molecular Science Graduate Program, Ryerson University, Toronto, Canada.,Department of Chemistry and Biology, Ryerson University, Toronto, Canada
| | | | - Akriti Prashar
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Canada.,Department of Cell and System Biology, University of Toronto Scarborough, Toronto, Canada
| | - Vanina Zaremberg
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Roberto J Botelho
- Molecular Science Graduate Program, Ryerson University, Toronto, Canada .,Department of Chemistry and Biology, Ryerson University, Toronto, Canada
| | - Mauricio R Terebiznik
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Canada .,Department of Cell and System Biology, University of Toronto Scarborough, Toronto, Canada
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48
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Qiu S, Leung A, Bo Y, Kozak RA, Anand SP, Warkentin C, Salambanga FDR, Cui J, Kobinger G, Kobasa D, Côté M. Ebola virus requires phosphatidylinositol (3,5) bisphosphate production for efficient viral entry. Virology 2017; 513:17-28. [PMID: 29031163 DOI: 10.1016/j.virol.2017.09.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/28/2017] [Accepted: 09/30/2017] [Indexed: 12/11/2022]
Abstract
For entry, Ebola virus (EBOV) requires the interaction of its viral glycoprotein with the cellular protein Niemann-Pick C1 (NPC1) which resides in late endosomes and lysosomes. How EBOV is trafficked and delivered to NPC1 and whether this is positively regulated during entry remain unclear. Here, we show that the PIKfyve-ArPIKfyve-Sac3 cellular complex, which is involved in the metabolism of phosphatidylinositol (3,5) bisphosphate (PtdIns(3,5)P2), is critical for EBOV infection. Although the expression of all subunits of the complex was required for efficient entry, PIKfyve kinase activity was specifically critical for entry by all pathogenic filoviruses. Inhibition of PIKfyve prevented colocalization of EBOV with NPC1 and led to virus accumulation in intracellular vesicles with characteristics of early endosomes. Importantly, genetically-encoded phosphoinositide probes revealed an increase in PtdIns(3,5)P2-positive vesicles in cells during EBOV entry. Taken together, our studies suggest that EBOV requires PtdIns(3,5)P2 production in cells to promote efficient delivery to NPC1.
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Affiliation(s)
- Shirley Qiu
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Anders Leung
- Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Canada
| | - Yuxia Bo
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Robert A Kozak
- Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Canada
| | - Sai Priya Anand
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Corina Warkentin
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Fabiola D R Salambanga
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Jennifer Cui
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Gary Kobinger
- Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Canada
| | - Darwyn Kobasa
- Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Canada; Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada
| | - Marceline Côté
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada.
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49
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Choy CH, Han BK, Botelho RJ. Phosphoinositide Diversity, Distribution, and Effector Function: Stepping Out of the Box. Bioessays 2017; 39. [PMID: 28977683 DOI: 10.1002/bies.201700121] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 08/31/2017] [Indexed: 12/26/2022]
Abstract
Phosphoinositides (PtdInsPs) modulate a plethora of functions including signal transduction and membrane trafficking. PtdInsPs are thought to consist of seven interconvertible species that localize to a specific organelle, to which they recruit a set of cognate effector proteins. Here, in reviewing the literature, we argue that this model needs revision. First, PtdInsPs can carry a variety of acyl chains, greatly boosting their molecular diversity. Second, PtdInsPs are more promiscuous in their localization than is usually acknowledged. Third, PtdInsP interconversion is likely achieved through kinase-phosphatase enzyme complexes that coordinate their activities and channel substrates without affecting bulk substrate population. Additionally, we contend that despite hundreds of PtdInsP effectors, our attention is biased toward few proteins. Lastly, we recognize that PtdInsPs can act to nucleate coincidence detection at the effector level, as in PDK1 and Akt. Overall, better integrated models of PtdInsP regulation and function are not only possible but needed.
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Affiliation(s)
- Christopher H Choy
- Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada M5B2K3.,Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada M5B2K3
| | - Bong-Kwan Han
- The Intelligent Synthetic Biology Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Roberto J Botelho
- Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada M5B2K3.,Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada M5B2K3
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50
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Gentil BJ, O'Ferrall E, Chalk C, Santana LF, Durham HD, Massie R. A New Mutation in FIG4 Causes a Severe Form of CMT4J Involving TRPV4 in the Pathogenic Cascade. J Neuropathol Exp Neurol 2017; 76:789-799. [PMID: 28859335 DOI: 10.1093/jnen/nlx062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Mutations in FIG4, coding for a phosphoinositol(3,5) bisphosphate 5' phosphatase and involved in vesicular trafficking and fusion, have been shown causing a recessive form of Charcot-Marie-Tooth (CMT). We have identified a novel intronic mutation in the FIG4 in a wheel-chair bound patient presenting with a severe form of CMT4J and provide a longitudinal study. Investigations indicated a demyelinating sensorimotor polyneuropathy with diffuse active denervation and severe axonal loss. Genetic testing revealed that the patient is heterozygous for 2 FIG4 mutations, p.I41T and a T > G transversion at IVS17-10, the latter predicted to cause a splicing defect. FIG4 was severely diminished in patient's fibroblasts indicating loss-of-function. Consistent with FIG4's function in phosphoinositol homeostasis and vesicular trafficking, fibroblasts contained multiple large vacuoles and vesicular organelles were abnormally dispersed. FIG4 deficiency has implications for turnover of membrane proteins. The transient receptor cation channel, TRPV4, accumulated at the plasma membrane of patient's fibroblasts due to slow turnover. Knocking down Fig4 in murine cultured motor neurons resulted in vacuolation and cell death. Inhibiting TRPV4 activity significantly preserved viability, although not correcting vesicular trafficking. In conclusion, we demonstrate a new FIG4 intronic mutation and, importantly, a functional interaction between FIG4 and TRPV4.
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Affiliation(s)
- Benoit J Gentil
- Department of Neurology and Neurosurgery & Montreal Neurological Institute, McGill University, Quebec, Canada; and Department of Physiology & Biophysics and Howard Hughes Medical Institute, Department of Pharmacology, University of Washington, Seattle, Washington
| | - Erin O'Ferrall
- Department of Neurology and Neurosurgery & Montreal Neurological Institute, McGill University, Quebec, Canada; and Department of Physiology & Biophysics and Howard Hughes Medical Institute, Department of Pharmacology, University of Washington, Seattle, Washington
| | - Colin Chalk
- Department of Neurology and Neurosurgery & Montreal Neurological Institute, McGill University, Quebec, Canada; and Department of Physiology & Biophysics and Howard Hughes Medical Institute, Department of Pharmacology, University of Washington, Seattle, Washington
| | - Luis F Santana
- Department of Neurology and Neurosurgery & Montreal Neurological Institute, McGill University, Quebec, Canada; and Department of Physiology & Biophysics and Howard Hughes Medical Institute, Department of Pharmacology, University of Washington, Seattle, Washington
| | - Heather D Durham
- Department of Neurology and Neurosurgery & Montreal Neurological Institute, McGill University, Quebec, Canada; and Department of Physiology & Biophysics and Howard Hughes Medical Institute, Department of Pharmacology, University of Washington, Seattle, Washington
| | - Rami Massie
- Department of Neurology and Neurosurgery & Montreal Neurological Institute, McGill University, Quebec, Canada; and Department of Physiology & Biophysics and Howard Hughes Medical Institute, Department of Pharmacology, University of Washington, Seattle, Washington
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