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Hu M, Feng X, Liu Q, Liu S, Huang F, Xu H. The ion channels of endomembranes. Physiol Rev 2024; 104:1335-1385. [PMID: 38451235 DOI: 10.1152/physrev.00025.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 02/20/2024] [Accepted: 02/25/2024] [Indexed: 03/08/2024] Open
Abstract
The endomembrane system consists of organellar membranes in the biosynthetic pathway [endoplasmic reticulum (ER), Golgi apparatus, and secretory vesicles] as well as those in the degradative pathway (early endosomes, macropinosomes, phagosomes, autophagosomes, late endosomes, and lysosomes). These endomembrane organelles/vesicles work together to synthesize, modify, package, transport, and degrade proteins, carbohydrates, and lipids, regulating the balance between cellular anabolism and catabolism. Large ion concentration gradients exist across endomembranes: Ca2+ gradients for most endomembrane organelles and H+ gradients for the acidic compartments. Ion (Na+, K+, H+, Ca2+, and Cl-) channels on the organellar membranes control ion flux in response to cellular cues, allowing rapid informational exchange between the cytosol and organelle lumen. Recent advances in organelle proteomics, organellar electrophysiology, and luminal and juxtaorganellar ion imaging have led to molecular identification and functional characterization of about two dozen endomembrane ion channels. For example, whereas IP3R1-3 channels mediate Ca2+ release from the ER in response to neurotransmitter and hormone stimulation, TRPML1-3 and TMEM175 channels mediate lysosomal Ca2+ and H+ release, respectively, in response to nutritional and trafficking cues. This review aims to summarize the current understanding of these endomembrane channels, with a focus on their subcellular localizations, ion permeation properties, gating mechanisms, cell biological functions, and disease relevance.
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Affiliation(s)
- Meiqin Hu
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Xinghua Feng
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Qiang Liu
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Siyu Liu
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Fangqian Huang
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Haoxing Xu
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States
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Gopaldass N, Chen KE, Collins B, Mayer A. Assembly and fission of tubular carriers mediating protein sorting in endosomes. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00746-8. [PMID: 38886588 DOI: 10.1038/s41580-024-00746-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/03/2024] [Indexed: 06/20/2024]
Abstract
Endosomes are central protein-sorting stations at the crossroads of numerous membrane trafficking pathways in all eukaryotes. They have a key role in protein homeostasis and cellular signalling and are involved in the pathogenesis of numerous diseases. Endosome-associated protein assemblies or coats collect transmembrane cargo proteins and concentrate them into retrieval domains. These domains can extend into tubular carriers, which then pinch off from the endosomal membrane and deliver the cargoes to appropriate subcellular compartments. Here we discuss novel insights into the structure of a number of tubular membrane coats that mediate the recruitment of cargoes into these carriers, focusing on sorting nexin-based coats such as Retromer, Commander and ESCPE-1. We summarize current and emerging views of how selective tubular endosomal carriers form and detach from endosomes by fission, highlighting structural aspects, conceptual challenges and open questions.
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Affiliation(s)
- Navin Gopaldass
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland.
| | - Kai-En Chen
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Brett Collins
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Andreas Mayer
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland.
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Murphy EA, Kleiner FH, Helliwell KE, Wheeler GL. Channels of Evolution: Unveiling Evolutionary Patterns in Diatom Ca 2+ Signalling. PLANTS (BASEL, SWITZERLAND) 2024; 13:1207. [PMID: 38732422 PMCID: PMC11085791 DOI: 10.3390/plants13091207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/09/2024] [Accepted: 04/15/2024] [Indexed: 05/13/2024]
Abstract
Diatoms are important primary producers in marine and freshwater environments, but little is known about the signalling mechanisms they use to detect changes in their environment. All eukaryotic organisms use Ca2+ signalling to perceive and respond to environmental stimuli, employing a range of Ca2+-permeable ion channels to facilitate the movement of Ca2+ across cellular membranes. We investigated the distribution of different families of Ca2+ channels in diatom genomes, with comparison to other members of the stramenopile lineage. The four-domain voltage-gated Ca2+ channels (Cav) are present in some centric diatoms but almost completely absent in pennate diatoms, whereas single-domain voltage-gated EukCatA channels were found in all diatoms. Glutamate receptors (GLRs) and pentameric ligand-gated ion channels (pLGICs) also appear to have been lost in several pennate species. Transient receptor potential (TRP) channels are present in all diatoms, but have not undergone the significant expansion seen in brown algae. All diatom species analysed lacked the mitochondrial uniporter (MCU), a highly conserved channel type found in many eukaryotes, including several stramenopile lineages. These results highlight the unique Ca2+-signalling toolkit of diatoms and indicate that evolutionary gains or losses of different Ca2+ channels may contribute to differences in cellular-signalling mechanisms between species.
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Affiliation(s)
- Eleanor A. Murphy
- Marine Biological Association, Plymouth PL1 2PB, UK (K.E.H.)
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | | | - Katherine E. Helliwell
- Marine Biological Association, Plymouth PL1 2PB, UK (K.E.H.)
- Department of Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - Glen L. Wheeler
- Marine Biological Association, Plymouth PL1 2PB, UK (K.E.H.)
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Karamooz E, Peterson J, Tammen A, Soma S, Kim SJ, Lewinsohn D. Calcium Signaling in MR1-Dependent Antigen Presentation of Mycobacterium tuberculosis. RESEARCH SQUARE 2023:rs.3.rs-3154465. [PMID: 37693580 PMCID: PMC10491339 DOI: 10.21203/rs.3.rs-3154465/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
MR1 is a ubiquitously expressed MHC-Ib molecule that presents microbial metabolites to MR1-restricted T cells, but there are differences in the antigen presentation pathway of an intracellular microbe compared to exogenous antigen. We have shown the importance of endosomal trafficking proteins in MR1-dependent presentation of Mycobacterium tuberculosis (Mtb). Two pore channels (TPCs) are endosomal calcium channels that regulate endosomal trafficking. Due to their location on endosomes, we hypothesized that TPCs could be required for MR1-dependent presentation of antigens derived from the intracellular microbe Mtb. We found that TPCs are critical for the presentation of Mtb by MR1; inhibition of TPCs had no effect on MR1 presentation of extracellular (exogenous) antigens, HLA-B presentation, or HLA-II presentation. Finally, we found that the calcium sensitive trafficking protein Synaptotagmin 7 was also key in the presentation of Mtb by MR1. This calcium-dependent endosomal pathway is a novel mechanism by which the immune system can sample intracellular antigens.
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Affiliation(s)
| | | | | | | | | | - David Lewinsohn
- Department of Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, OR 97239, USA
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Božić M, Pirnat S, Fink K, Potokar M, Kreft M, Zorec R, Stenovec M. Ketamine Reduces the Surface Density of the Astroglial Kir4.1 Channel and Inhibits Voltage-Activated Currents in a Manner Similar to the Action of Ba 2+ on K + Currents. Cells 2023; 12:1360. [PMID: 37408194 DOI: 10.3390/cells12101360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 07/07/2023] Open
Abstract
A single sub-anesthetic dose of ketamine evokes rapid and long-lasting beneficial effects in patients with a major depressive disorder. However, the mechanisms underlying this effect are unknown. It has been proposed that astrocyte dysregulation of extracellular K+ concentration ([K+]o) alters neuronal excitability, thus contributing to depression. We examined how ketamine affects inwardly rectifying K+ channel Kir4.1, the principal regulator of K+ buffering and neuronal excitability in the brain. Cultured rat cortical astrocytes were transfected with plasmid-encoding fluorescently tagged Kir4.1 (Kir4.1-EGFP) to monitor the mobility of Kir4.1-EGFP vesicles at rest and after ketamine treatment (2.5 or 25 µM). Short-term (30 min) ketamine treatment reduced the mobility of Kir4.1-EGFP vesicles compared with the vehicle-treated controls (p < 0.05). Astrocyte treatment (24 h) with dbcAMP (dibutyryl cyclic adenosine 5'-monophosphate, 1 mM) or [K+]o (15 mM), which increases intracellular cAMP, mimicked the ketamine-evoked reduction of mobility. Live cell immunolabelling and patch-clamp measurements in cultured mouse astrocytes revealed that short-term ketamine treatment reduced the surface density of Kir4.1 and inhibited voltage-activated currents similar to Ba2+ (300 µM), a Kir4.1 blocker. Thus, ketamine attenuates Kir4.1 vesicle mobility, likely via a cAMP-dependent mechanism, reduces Kir4.1 surface density, and inhibits voltage-activated currents similar to Ba2+, known to block Kir4.1 channels.
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Affiliation(s)
- Mićo Božić
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
- Department of Medical Oncology, Institute of Oncology Ljubljana, Zaloška 2, 1000 Ljubljana, Slovenia
| | - Samo Pirnat
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
- Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia
| | - Katja Fink
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
| | - Maja Potokar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
- Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia
| | - Marko Kreft
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
- Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia
- Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
- Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia
| | - Matjaž Stenovec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
- Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia
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Just A, Mallmann RT, Grossmann S, Sleman F, Klugbauer N. Two-pore channel protein TPC1 is a determining factor for the adaptation of proximal tubular phosphate handling. Acta Physiol (Oxf) 2023; 237:e13914. [PMID: 36599408 DOI: 10.1111/apha.13914] [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: 06/10/2022] [Revised: 10/27/2022] [Accepted: 01/02/2023] [Indexed: 01/06/2023]
Abstract
AIM Two-pore channels (TPCs) constitute a small family of cation channels expressed in endo-lysosomal compartments. TPCs have been characterized as critical elements controlling Ca2+ -mediated vesicular membrane fusion and thereby regulating endo-lysosomal vesicle trafficking. Exo- and endocytotic trafficking and lysosomal degradation are major mechanisms of adaption of epithelial transport. A prime example of highly regulated epithelial transport is the tubular system of the kidney. We therefore studied the localization of TPC protein 1 (TPC1) in the kidney and its functional role in the dynamic regulation of tubular transport. METHODS Immunohistochemistry in combination with tubular markers were used to investigate TPC1 expression in proximal and distal tubules. The excretion of phosphate and ammonium, as well as urine volume and pH were studied in vivo, in response to dynamic challenges induced by bolus injection of parathyroid hormone or acid-base transitions via consecutive infusion of NaCl, Na2 CO3 , and NH4 Cl. RESULTS In TPC1-deficient mice, the PTH-induced rise in phosphate excretion was prolonged and exaggerated, and its recovery delayed in comparison with wildtype littermates. In the acid-base transition experiment, TPC1-deficient mice showed an identical rise in phosphate excretion in response to Na2 CO3 compared with wildtypes, but a delayed NH4Cl-induced recovery. Ammonium-excretion decreased with Na2 CO3 , and increased with NH4 Cl, but without differences between genotypes. CONCLUSIONS We conclude that TPC1 is expressed subapically in the proximal but not distal tubule and plays an important role in the dynamic adaptation of proximal tubular phosphate reabsorption towards enhanced, but not reduced absorption.
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Affiliation(s)
- Armin Just
- Institut für Physiologie I, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Robert T Mallmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Sonja Grossmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Faten Sleman
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Norbert Klugbauer
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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7
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Steiner P, Arlt E, Boekhoff I, Gudermann T, Zierler S. TPC Functions in the Immune System. Handb Exp Pharmacol 2023; 278:71-92. [PMID: 36639434 DOI: 10.1007/164_2022_634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Two-pore channels (TPCs) are novel intracellular cation channels, which play a key role in numerous (patho-)physiological and immunological processes. In this chapter, we focus on their function in immune cells and immune reactions. Therefore, we first give an overview of the cellular immune response and the partaking immune cells. Second, we concentrate on ion channels which in the past have been shown to play an important role in the regulation of immune cells. The main focus is then directed to TPCs, which are primarily located in the membranes of acidic organelles, such as lysosomes or endolysosomes but also certain other vesicles. They regulate Ca2+ homeostasis and thus Ca2+ signaling in immune cells. Due to this important functional role, TPCs are enjoying increasing attention within the field of immunology in the last few decades but are also becoming more pertinent as pharmacological targets for the treatment of pro-inflammatory diseases such as allergic hypersensitivity. However, to uncover the precise molecular mechanism of TPCs in immune cell responses, further molecular, genetic, and ultrastructural investigations on TPCs are necessary, which then may pave the way to develop novel therapeutic strategies to treat diseases such as anaphylaxis more specifically.
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Affiliation(s)
- Philip Steiner
- Institute of Pharmacology, Faculty of Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Elisabeth Arlt
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ingrid Boekhoff
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Susanna Zierler
- Institute of Pharmacology, Faculty of Medicine, Johannes Kepler University Linz, Linz, Austria.
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany.
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8
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Rautenberg S, Keller M, Leser C, Chen CC, Bracher F, Grimm C. Expanding the Toolbox: Novel Modulators of Endolysosomal Cation Channels. Handb Exp Pharmacol 2023; 278:249-276. [PMID: 35902436 DOI: 10.1007/164_2022_605] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Functional characterization of endolysosomal ion channels is challenging due to their intracellular location. With recent advances in endolysosomal patch clamp technology, it has become possible to directly measure ion channel currents across endolysosomal membranes. Members of the transient receptor potential (TRP) cation channel family, namely the endolysosomal TRPML channels (TRPML1-3), also called mucolipins, as well as the distantly related two-pore channels (TPCs) have recently been characterized in more detail with endolysosomal patch clamp techniques. However, answers to many physiological questions require work in intact cells or animal models. One major obstacle thereby is that the known endogenous ligands of TRPMLs and TPCs are anionic in nature and thus impermeable for cell membranes. Microinjection, on the other hand, is technically demanding. There is also a risk of losing essential co-factors for channel activation or inhibition in isolated preparations. Therefore, lipophilic, membrane-permeable small-molecule activators and inhibitors for TRPMLs and TPCs are urgently needed. Here, we describe and discuss the currently available small-molecule modulators of TRPMLs and TPCs.
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Affiliation(s)
- Susanne Rautenberg
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany
| | - Marco Keller
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany
| | - Charlotte Leser
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany
| | - Cheng-Chang Chen
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany
| | - Franz Bracher
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany.
| | - Christian Grimm
- Department of Pharmacology and Toxicology, Medical Faculty, Ludwig-Maximilians-University, Munich, Germany.
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Patel S, Zissimopoulos S, Marchant JS. Endo-Lysosomal Two-Pore Channels and Their Protein Partners. Handb Exp Pharmacol 2023; 278:199-214. [PMID: 35902438 DOI: 10.1007/164_2022_601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Two-pore channels are ion channels expressed on acidic organelles such as the various vesicles that constitute the endo-lysosomal system. They are permeable to Ca2+ and Na+ and activated by the second messenger NAADP as well as the phosphoinositide, PI(3,5)P2 and/or voltage. Here, we review the proteins that interact with these channels including recently identified NAADP receptors.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, London, UK.
| | | | - Jonathan S Marchant
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
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Enrich C, Lu A, Tebar F, Rentero C, Grewal T. Ca 2+ and Annexins - Emerging Players for Sensing and Transferring Cholesterol and Phosphoinositides via Membrane Contact Sites. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:393-438. [PMID: 36988890 DOI: 10.1007/978-3-031-21547-6_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Maintaining lipid composition diversity in membranes from different organelles is critical for numerous cellular processes. However, many lipids are synthesized in the endoplasmic reticulum (ER) and require delivery to other organelles. In this scenario, formation of membrane contact sites (MCS) between neighbouring organelles has emerged as a novel non-vesicular lipid transport mechanism. Dissecting the molecular composition of MCS identified phosphoinositides (PIs), cholesterol, scaffolding/tethering proteins as well as Ca2+ and Ca2+-binding proteins contributing to MCS functioning. Compelling evidence now exists for the shuttling of PIs and cholesterol across MCS, affecting their concentrations in distinct membrane domains and diverse roles in membrane trafficking. Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) at the plasma membrane (PM) not only controls endo-/exocytic membrane dynamics but is also critical in autophagy. Cholesterol is highly concentrated at the PM and enriched in recycling endosomes and Golgi membranes. MCS-mediated cholesterol transfer is intensely researched, identifying MCS dysfunction or altered MCS partnerships to correlate with de-regulated cellular cholesterol homeostasis and pathologies. Annexins, a conserved family of Ca2+-dependent phospholipid binding proteins, contribute to tethering and untethering events at MCS. In this chapter, we will discuss how Ca2+ homeostasis and annexins in the endocytic compartment affect the sensing and transfer of cholesterol and PIs across MCS.
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Affiliation(s)
- Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel⋅lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
- Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain.
| | - Albert Lu
- Departament de Biomedicina, Unitat de Biologia Cel⋅lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Francesc Tebar
- Departament de Biomedicina, Unitat de Biologia Cel⋅lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cel⋅lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Thomas Grewal
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
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11
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Two-pore channels: going with the flows. Biochem Soc Trans 2022; 50:1143-1155. [PMID: 35959977 PMCID: PMC9444070 DOI: 10.1042/bst20220229] [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: 06/17/2022] [Revised: 07/21/2022] [Accepted: 07/25/2022] [Indexed: 11/26/2022]
Abstract
In recent years, our understanding of the structure, mechanisms and functions of the endo-lysosomal TPC (two-pore channel) family have grown apace. Gated by the second messengers, NAADP and PI(3,5)P2, TPCs are an integral part of fundamental signal-transduction pathways, but their array and plasticity of cation conductances (Na+, Ca2+, H+) allow them to variously signal electrically, osmotically or chemically. Their relative tissue- and organelle-selective distribution, together with agonist-selective ion permeabilities provides a rich palette from which extracellular stimuli can choose. TPCs are emerging as mediators of immunity, cancer, metabolism, viral infectivity and neurodegeneration as this short review attests.
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12
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The Three Two-Pore Channel Subtypes from Rabbit Exhibit Distinct Sensitivity to Phosphoinositides, Voltage, and Extracytosolic pH. Cells 2022; 11:cells11132006. [PMID: 35805090 PMCID: PMC9265530 DOI: 10.3390/cells11132006] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/17/2022] [Accepted: 06/19/2022] [Indexed: 01/14/2023] Open
Abstract
Two pore channels (TPCs) are implicated in vesicle trafficking, virus infection, and autophagy regulation. As Na+- or Ca2+-permeable channels, TPCs have been reported to be activated by NAADP, PI(3,5)P2, and/or high voltage. However, a comparative study on the function and regulation of the three mammalian TPC subtypes is currently lacking. Here, we used the electrophysiological recording of enlarged endolysosome vacuoles, inside-out and outside-out membrane patches to examine the three TPCs of rabbit (Oryctolagus cuniculus, or Oc) heterologously expressed in HEK293 cells. While PI(3,5)P2 evoked Na+ currents with a potency order of OcTPC1 > OcTPC3 > OcTPC2, only OcTPC2 displayed a strict dependence on PI(3,5)P2. Both OcTPC1 and OcTPC3 were activatable by PI3P and OcTPC3 was also activated by additional phosphoinositide species. While OcTPC2 was voltage-independent, OcTPC1 and OcTPC3 showed voltage dependence with OcTPC3 depending on high positive voltages. Finally, while OcTPC2 preferred a luminal pH of 4.6−6.0 in endolysosomes, OcTPC1 was strongly inhibited by extracytosolic pH 5.0 in both voltage-dependent and -independent manners, and OcTPC3 was inhibited by pH 6.0 but potentiated by pH 8.0. Thus, the three OcTPCs form phosphoinositide-activated Na+ channels with different ligand selectivity, voltage dependence, and extracytosolic pH sensitivity, which likely are optimally tuned for function in specific endolysosomal populations.
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13
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Steiner P, Arlt E, Boekhoff I, Gudermann T, Zierler S. Two-Pore Channels Regulate Inter-Organellar Ca 2+ Homeostasis in Immune Cells. Cells 2022; 11:1465. [PMID: 35563771 PMCID: PMC9103377 DOI: 10.3390/cells11091465] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/13/2022] [Accepted: 04/16/2022] [Indexed: 02/01/2023] Open
Abstract
Two-pore channels (TPCs) are ligand-gated cation-selective ion channels that are preserved in plant and animal cells. In the latter, TPCs are located in membranes of acidic organelles, such as endosomes, lysosomes, and endolysosomes. Here, we focus on the function of these unique ion channels in mast cells, which are leukocytes that mature from myeloid hematopoietic stem cells. The cytoplasm of these innate immune cells contains a large number of granules that comprise messenger substances, such as histamine and heparin. Mast cells, along with basophil granulocytes, play an essential role in anaphylaxis and allergic reactions by releasing inflammatory mediators. Signaling in mast cells is mainly regulated via the release of Ca2+ from the endoplasmic reticulum as well as from acidic compartments, such as endolysosomes. For the crosstalk of these organelles TPCs seem essential. Allergic reactions and anaphylaxis were previously shown to be associated with the endolysosomal two-pore channel TPC1. The release of histamine, controlled by intracellular Ca2+ signals, was increased upon genetic or pharmacologic TPC1 inhibition. Conversely, stimulation of TPC channel activity by one of its endogenous ligands, namely nicotinic adenine dinucleotide phosphate (NAADP) or phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2), were found to trigger the release of Ca2+ from the endolysosomes; thereby improving the effect of TPC1 on regulated mast cell degranulation. In this review we discuss the importance of TPC1 for regulating Ca2+ homeostasis in mast cells and the overall potential of TPC1 as a pharmacological target in anti-inflammatory therapy.
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Affiliation(s)
- Philip Steiner
- Institute of Pharmacology, Medical Faculty, Johannes Kepler University Linz, 4020 Linz, Austria;
| | - Elisabeth Arlt
- Walther Straub Institute of Pharmacology and Toxicology, Medical Faculty, Ludwig Maximilians University Munich, 80336 Munich, Germany; (E.A.); (I.B.); (T.G.)
| | - Ingrid Boekhoff
- Walther Straub Institute of Pharmacology and Toxicology, Medical Faculty, Ludwig Maximilians University Munich, 80336 Munich, Germany; (E.A.); (I.B.); (T.G.)
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Medical Faculty, Ludwig Maximilians University Munich, 80336 Munich, Germany; (E.A.); (I.B.); (T.G.)
| | - Susanna Zierler
- Institute of Pharmacology, Medical Faculty, Johannes Kepler University Linz, 4020 Linz, Austria;
- Walther Straub Institute of Pharmacology and Toxicology, Medical Faculty, Ludwig Maximilians University Munich, 80336 Munich, Germany; (E.A.); (I.B.); (T.G.)
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14
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Chen CC, Krogsaeter E, Kuo CY, Huang MC, Chang SY, Biel M. Endolysosomal cation channels point the way towards precision medicine of cancer and infectious diseases. Biomed Pharmacother 2022; 148:112751. [PMID: 35240524 DOI: 10.1016/j.biopha.2022.112751] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 11/02/2022] Open
Abstract
Infectious diseases and cancer are among the key medical challenges that humankind is facing today. A growing amount of evidence suggests that ion channels in the endolysosomal system play a crucial role in the pathology of both groups of diseases. The development of advanced patch-clamp technologies has allowed us to directly characterize ion fluxes through endolysosomal ion channels in their native environments. Endolysosomes are essential organelles for intracellular transport, digestion and metabolism, and maintenance of homeostasis. The endolysosomal ion channels regulate the function of the endolysosomal system through four basic mechanisms: calcium release, control of membrane potential, pH change, and osmolarity regulation. In this review, we put particular emphasis on the endolysosomal cation channels, including TPC2 and TRPML2, which are particularly important in monocyte function. We discuss existing endogenous and synthetic ligands of these channels and summarize current knowledge of their impact on channel activity and function in different cell types. Moreover, we summarize recent findings on the importance of TPC2 and TRPML2 channels as potential drug targets for the prevention and treatment of the emerging infectious diseases and cancer.
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Affiliation(s)
- Cheng-Chang Chen
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan.
| | | | - Ching-Ying Kuo
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Min-Chuan Huang
- Graduate Institute of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Sui-Yuan Chang
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Martin Biel
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
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15
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Gunaratne GS, Marchant JS. The ins and outs of virus trafficking through acidic Ca 2+ stores. Cell Calcium 2022; 102:102528. [PMID: 35033909 PMCID: PMC8860173 DOI: 10.1016/j.ceca.2022.102528] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 12/20/2022]
Abstract
Many viruses exploit host-cell Ca2+ signaling processes throughout their life cycle. This is especially relevant for viruses that translocate through the endolysosomal system, where cellular infection is keyed to the microenvironment of these acidic Ca2+ stores and Ca2+-dependent trafficking pathways. As regulators of the endolysosomal ionic milieu and trafficking dynamics, two families of endolysosomal Ca2+-permeable cation channels - two pore channels (TPCs) and transient receptor potential mucolipins (TRPMLs) - have emerged as important host-cell factors in viral entry. Here, we review: (i) current evidence implicating Ca2+ signaling in viral translocation through the endolysosomal system, (ii) the roles of these ion channels in supporting cellular infection by different viruses, and (iii) areas for future research that will help define the potential of TPC and TRPML ligands as progressible antiviral agents.
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Affiliation(s)
- Gihan S Gunaratne
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee WI 53226, USA.
| | - Jonathan S Marchant
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee WI 53226, USA
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16
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Krogsaeter E, Rosato AS, Grimm C. TRPMLs and TPCs: targets for lysosomal storage and neurodegenerative disease therapy? Cell Calcium 2022; 103:102553. [DOI: 10.1016/j.ceca.2022.102553] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 12/25/2022]
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17
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Spix B, Jeridi A, Ansari M, Yildirim AÖ, Schiller HB, Grimm C. Endolysosomal Cation Channels and Lung Disease. Cells 2022; 11:304. [PMID: 35053420 PMCID: PMC8773812 DOI: 10.3390/cells11020304] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/20/2021] [Accepted: 12/25/2021] [Indexed: 12/28/2022] Open
Abstract
Endolysosomal cation channels are emerging as key players of endolysosomal function such as endolysosomal trafficking, fusion/fission, lysosomal pH regulation, autophagy, lysosomal exocytosis, and endocytosis. Diseases comprise lysosomal storage disorders (LSDs) and neurodegenerative diseases, metabolic diseases, pigmentation defects, cancer, immune disorders, autophagy related diseases, infectious diseases and many more. Involvement in lung diseases has not been a focus of attention so far but recent developments in the field suggest critical functions in lung physiology and pathophysiology. Thus, loss of TRPML3 was discovered to exacerbate emphysema formation and cigarette smoke induced COPD due to dysregulated matrix metalloproteinase 12 (MMP-12) levels in the extracellular matrix of the lung, a known risk factor for emphysema/COPD. While direct lung function measurements with the exception of TRPML3 are missing for other endolysosomal cation channels or channels expressed in lysosome related organelles (LRO) in the lung, links between those channels and important roles in lung physiology have been established such as the role of P2X4 in surfactant release from alveolar epithelial Type II cells. Other channels with demonstrated functions and disease relevance in the lung such as TRPM2, TRPV2, or TRPA1 may mediate their effects due to plasma membrane expression but evidence accumulates that these channels might also be expressed in endolysosomes, suggesting additional and/or dual roles of these channels in cell and intracellular membranes. We will discuss here the current knowledge on cation channels residing in endolysosomes or LROs with respect to their emerging roles in lung disease.
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Affiliation(s)
- Barbara Spix
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-University, 80336 Munich, Germany;
| | - Aicha Jeridi
- Pneumology Center, Institute of Lung Biology and Disease, Helmholtz Zentrum München, 85764 Munich, Germany; (A.J.); (M.A.); (A.Ö.Y.); (H.B.S.)
| | - Meshal Ansari
- Pneumology Center, Institute of Lung Biology and Disease, Helmholtz Zentrum München, 85764 Munich, Germany; (A.J.); (M.A.); (A.Ö.Y.); (H.B.S.)
| | - Ali Önder Yildirim
- Pneumology Center, Institute of Lung Biology and Disease, Helmholtz Zentrum München, 85764 Munich, Germany; (A.J.); (M.A.); (A.Ö.Y.); (H.B.S.)
| | - Herbert B. Schiller
- Pneumology Center, Institute of Lung Biology and Disease, Helmholtz Zentrum München, 85764 Munich, Germany; (A.J.); (M.A.); (A.Ö.Y.); (H.B.S.)
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-University, 80336 Munich, Germany;
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18
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Jin X, Zhang Y, Alharbi A, Hanbashi A, Alhoshani A, Parrington J. Targeting Two-Pore Channels: Current Progress and Future Challenges. Trends Pharmacol Sci 2021; 41:582-594. [PMID: 32679067 PMCID: PMC7365084 DOI: 10.1016/j.tips.2020.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/04/2020] [Accepted: 06/04/2020] [Indexed: 12/19/2022]
Abstract
Two-pore channels (TPCs) are cation-permeable channels located on endolysosomal membranes and important mediators of intracellular Ca2+ signalling. TPCs are involved in various pathophysiological processes, including cell growth and development, metabolism, and cancer progression. Most studies of TPCs have used TPC–/– cell or whole-animal models, or Ned-19, an indirect inhibitor. The TPC activation mechanism remains controversial, which has made it difficult to develop selective modulators. Recent studies of TPC structure and their interactomes are aiding the development of direct pharmacological modulators. This process is still in its infancy, but will facilitate future research and TPC targeting for therapeutical purposes. Here, we review the progress of current research into TPCs, including recent insights into their structures, functional roles, mechanisms of activation, and pharmacological modulators. Two-pore channel (TPC)-mediated endolysosomal Ca2+ signalling regulates a variety of processes, including cell proliferation, differentiation, metabolism, viral infection, and cardiac function. Despite the well-established model that TPCs are Ca2+-selective channels indirectly activated by nicotinic acid adenine dinucleotide phosphate (NAADP), it has also been proposed that TPCs as Na+ channels are activated directly by phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2]. 3D structures of mouse TPC1 and human TPC2 were recently determined, which made it possible for structure-based virtual screening methods to identify pharmacological modulators of TPC. Recent identification by high-throughput screens of pharmacological modulators that target TPCs will help reveal the molecular mechanisms underlying the role of endolysosomal Ca2+ signalling in different pathophysiological processes, and to develop new therapeutics.
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Affiliation(s)
- Xuhui Jin
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Yuxuan Zhang
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Abeer Alharbi
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Ali Hanbashi
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Ali Alhoshani
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11454, Kingdom of Saudi Arabia
| | - John Parrington
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK.
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19
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Two-Pore Channels Regulate Expression of Various Receptors and Their Pathway-Related Proteins in Multiple Ways. Cells 2021; 10:cells10071807. [PMID: 34359976 PMCID: PMC8307395 DOI: 10.3390/cells10071807] [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: 06/16/2021] [Revised: 07/13/2021] [Accepted: 07/14/2021] [Indexed: 11/17/2022] Open
Abstract
Two-pore channels (TPCs) constitute a small family of ion channels within membranes of intracellular acidic compartments, such as endosomes and lysosomes. They were shown to provide transient and locally restricted Ca2+-currents, likely responsible for fusion and/or fission events of endolysosomal membranes and thereby for intracellular vesicle trafficking. Genetic deletion of TPCs not only affects endocytosis, recycling, and degradation of various surface receptors but also uptake and impact of bacterial protein toxins and entry and intracellular processing of some types of viruses. This review points to important examples of these trafficking defects on one part but mainly focuses on the resulting impact of the TPC inactivation on receptor expression and receptor signaling. Thus, a detailed RNA sequencing analysis using TPC1-deficient fibroblasts uncovered a multitude of changes in the expression levels of surface receptors and their pathway-related signaling proteins. We refer to several classes of receptors such as EGF, TGF, and insulin as well as proteins involved in endocytosis.
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20
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Hu W, Zhao F, Chen L, Ni J, Jiang Y. NAADP-induced intracellular calcium ion is mediated by the TPCs (two-pore channels) in hypoxia-induced pulmonary arterial hypertension. J Cell Mol Med 2021; 25:7485-7499. [PMID: 34263977 PMCID: PMC8335677 DOI: 10.1111/jcmm.16783] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 06/21/2021] [Accepted: 06/24/2021] [Indexed: 12/12/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is a form of obstructive vascular disease. Chronic hypoxic exposure leads to excessive proliferation of pulmonary arterial smooth muscle cells and pulmonary arterial endothelial cells. This condition can potentially be aggravated by [Ca2+] i mobilization. In the present study, hypoxia exposure of rat's model was established. Two‐pore segment channels (TPCs) silencing was achieved in rats' models by injecting Lsh‐TPC1 or Lsh‐TPC2. The effects of TPC1/2 silencing on PAH were evaluated by H&E staining detecting pulmonary artery wall thickness and ELISA assay kit detecting NAADP concentrations in lung tissues. TPC1/2 silencing was achieved in PASMCs and PAECs, and cell proliferation was detected by MTT and BrdU incorporation assays. As the results shown, NAADP‐activated [Ca2+]i shows to be mediated via two‐pore segment channels (TPCs) in PASMCs, with TPC1 being the dominant subtype. NAADP generation and TPC1/2 mRNA and protein levels were elevated in the hypoxia‐induced rat PAH model; NAADP was positively correlated with TPC1 and TPC2 expression, respectively. In vivo, Lsh‐TPC1 or Lsh‐TPC2 infection significantly improved the mean pulmonary artery pressure and PAH morphology. In vitro, TPC1 silencing inhibited NAADP‐AM‐induced PASMC proliferation and [Ca2+]i in PASMCs, whereas TPC2 silencing had minor effects during this process; TPC2 silencing attenuated NAADP‐AM‐ induced [Ca2+]i and ECM in endothelial cells, whereas TPC1 silencing barely ensued any physiological changes. In conclusion, TPC1/2 might provide a unifying mechanism within pulmonary arterial hypertension, which can potentially be regarded as a therapeutic target.
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Affiliation(s)
- Wen Hu
- Respiratory Medicine, Hunan Provincial People's Hospital, Changsha, China
| | - Fei Zhao
- Respiratory Medicine, Hunan Provincial People's Hospital, Changsha, China
| | - Ling Chen
- Respiratory Medicine, Hunan Provincial People's Hospital, Changsha, China
| | - Jiamin Ni
- Respiratory Medicine, Hunan Provincial People's Hospital, Changsha, China
| | - Yongliang Jiang
- Respiratory Medicine, Hunan Provincial People's Hospital, Changsha, China
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21
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Ritter M, Bresgen N, Kerschbaum HH. From Pinocytosis to Methuosis-Fluid Consumption as a Risk Factor for Cell Death. Front Cell Dev Biol 2021; 9:651982. [PMID: 34249909 PMCID: PMC8261248 DOI: 10.3389/fcell.2021.651982] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/29/2021] [Indexed: 12/11/2022] Open
Abstract
The volumes of a cell [cell volume (CV)] and its organelles are adjusted by osmoregulatory processes. During pinocytosis, extracellular fluid volume equivalent to its CV is incorporated within an hour and membrane area equivalent to the cell's surface within 30 min. Since neither fluid uptake nor membrane consumption leads to swelling or shrinkage, cells must be equipped with potent volume regulatory mechanisms. Normally, cells respond to outwardly or inwardly directed osmotic gradients by a volume decrease and increase, respectively, i.e., they shrink or swell but then try to recover their CV. However, when a cell death (CD) pathway is triggered, CV persistently decreases in isotonic conditions in apoptosis and it increases in necrosis. One type of CD associated with cell swelling is due to a dysfunctional pinocytosis. Methuosis, a non-apoptotic CD phenotype, occurs when cells accumulate too much fluid by macropinocytosis. In contrast to functional pinocytosis, in methuosis, macropinosomes neither recycle nor fuse with lysosomes but with each other to form giant vacuoles, which finally cause rupture of the plasma membrane (PM). Understanding methuosis longs for the understanding of the ionic mechanisms of cell volume regulation (CVR) and vesicular volume regulation (VVR). In nascent macropinosomes, ion channels and transporters are derived from the PM. Along trafficking from the PM to the perinuclear area, the equipment of channels and transporters of the vesicle membrane changes by retrieval, addition, and recycling from and back to the PM, causing profound changes in vesicular ion concentrations, acidification, and-most importantly-shrinkage of the macropinosome, which is indispensable for its proper targeting and cargo processing. In this review, we discuss ion and water transport mechanisms with respect to CVR and VVR and with special emphasis on pinocytosis and methuosis. We describe various aspects of the complex mutual interplay between extracellular and intracellular ions and ion gradients, the PM and vesicular membrane, phosphoinositides, monomeric G proteins and their targets, as well as the submembranous cytoskeleton. Our aim is to highlight important cellular mechanisms, components, and processes that may lead to methuotic CD upon their derangement.
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Affiliation(s)
- Markus Ritter
- Center for Physiology, Pathophysiology and Biophysics, Institute for Physiology and Pathophysiology, Paracelsus Medical University, Salzburg, Austria
- Institute for Physiology and Pathophysiology, Paracelsus Medical University, Nuremberg, Germany
- Gastein Research Institute, Paracelsus Medical University, Salzburg, Austria
- Ludwig Boltzmann Institute for Arthritis und Rehabilitation, Salzburg, Austria
- Kathmandu University School of Medical Sciences, Dhulikhel, Nepal
| | - Nikolaus Bresgen
- Department of Biosciences, University of Salzburg, Salzburg, Austria
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22
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Morgan AJ, Davis LC, Galione A. Choreographing endo-lysosomal Ca 2+ throughout the life of a phagosome. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119040. [PMID: 33872669 DOI: 10.1016/j.bbamcr.2021.119040] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/05/2021] [Accepted: 04/07/2021] [Indexed: 12/20/2022]
Abstract
The emergence of endo-lysosomes as ubiquitous Ca2+ stores with their unique cohort of channels has resulted in their being implicated in a growing number of processes in an ever-increasing number of cell types. The architectural and regulatory constraints of these acidic Ca2+ stores distinguishes them from other larger Ca2+ sources such as the ER and influx across the plasma membrane. In view of recent advances in the understanding of the modes of operation, we discuss phagocytosis as a template for how endo-lysosomal Ca2+ signals (generated via TPC and TRPML channels) can be integrated in multiple sophisticated ways into biological processes. Phagocytosis illustrates how different endo-lysosomal Ca2+ signals drive different phases of a process, and how these can be altered by disease or infection.
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Affiliation(s)
- Anthony J Morgan
- Department of Pharmacology, University of Oxford, Mansfield Park, Oxford OX1 3QT, UK.
| | - Lianne C Davis
- Department of Pharmacology, University of Oxford, Mansfield Park, Oxford OX1 3QT, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Park, Oxford OX1 3QT, UK.
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23
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Chadwick SR, Grinstein S, Freeman SA. From the inside out: Ion fluxes at the centre of endocytic traffic. Curr Opin Cell Biol 2021; 71:77-86. [PMID: 33706237 DOI: 10.1016/j.ceb.2021.02.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/19/2021] [Accepted: 02/04/2021] [Indexed: 12/15/2022]
Abstract
Endocytic traffic is a complex and elegant operation involving cargo sorting, membrane budding and tubulation, generation of force, and the formation of organellar contacts. The role of specific proteins and lipids in these processes has been studied extensively. By comparison, precious little is understood about the contribution of the endocytic fluid to these events, despite much evidence that alteration of the contents can severely affect membrane traffic along the endocytic pathway. In particular, it has long been appreciated that dissipation of ionic gradients arrests endosome-to-lysosome maturation. How cells sense inorganic ions and transmit this information have remained largely enigmatic. Herein, we review the experimental findings that reveal an intimate association between luminal ions, their transport, and endocytic traffic. We then discuss the ionic sensors and the mechanisms proposed to convert ion concentrations into protein-based trafficking events, highlighting the current paucity of convincing explanations.
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Affiliation(s)
- Sarah R Chadwick
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON, M5G 0A4, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Canada.
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Canada.
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24
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Müller T, Grossmann S, Mallmann RT, Rommel C, Hein L, Klugbauer N. Two-pore channels affect EGF receptor signaling by receptor trafficking and expression. iScience 2021; 24:102099. [PMID: 33644717 PMCID: PMC7887427 DOI: 10.1016/j.isci.2021.102099] [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: 05/20/2020] [Revised: 11/30/2020] [Accepted: 01/20/2021] [Indexed: 01/09/2023] Open
Abstract
Two-pore channels (TPCs) are key components for regulating Ca2+ current from endosomes and lysosomes to the cytosol. This locally restricted Ca2+ current forms the basis for fusion and fission events between endolysosomal membranes and thereby for intracellular trafficking processes. Here, we study the function of TPC1 and TPC2 for uptake, recycling, and degradation of epidermal growth factor receptor (EGFR) using a set of TPC knockout cells. RNA sequencing analysis revealed multiple changes in the expression levels of EGFR pathway-related genes in TPC1-deficient cells. We propose that a prolonged presence of activated EGFRs in endolysosomal signaling platforms, caused by genetic inactivation of TPCs, does not only affect EGFR signaling pathways but also increases de novo synthesis of EGFR. Increased basal phospho-c-Jun levels contribute to the high EGFR expression in TPC-deficient cells. Our data point to a role of TPCs not only as important regulators for the EGFR transportation network but also for EGFR-signaling and expression. Two-pore channels differently affect intracellular trafficking of EGF receptors Deletion of TPCs prolongs EGFR signaling in endolysosomal platforms TPCs affect expression of EGFR downstream signaling components JNK signaling contributes to increased EGFR expression in TPC-deficient cells
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Affiliation(s)
- Thomas Müller
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Fakultät für Medizin, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104 Freiburg, Germany
| | - Sonja Grossmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Fakultät für Medizin, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104 Freiburg, Germany
| | - Robert Theodor Mallmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Fakultät für Medizin, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104 Freiburg, Germany
| | - Carolin Rommel
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Fakultät für Medizin, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104 Freiburg, Germany
| | - Lutz Hein
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Fakultät für Medizin, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104 Freiburg, Germany
| | - Norbert Klugbauer
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Fakultät für Medizin, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104 Freiburg, Germany
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25
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Moccia F, Negri S, Faris P, Perna A, De Luca A, Soda T, Berra-Romani R, Guerra G. Targeting Endolysosomal Two-Pore Channels to Treat Cardiovascular Disorders in the Novel COronaVIrus Disease 2019. Front Physiol 2021; 12:629119. [PMID: 33574769 PMCID: PMC7870486 DOI: 10.3389/fphys.2021.629119] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/07/2021] [Indexed: 12/15/2022] Open
Abstract
Emerging evidence hints in favor of a life-threatening link between severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and the cardiovascular system. SARS-CoV-2 may result in dramatic cardiovascular complications, whereas the severity of COronaVIrus Disease 2019 (COVID-19) and the incidence of fatalities tend to increase in patients with pre-existing cardiovascular complications. SARS-CoV-2 is internalized into the host cells by endocytosis and may then escape the endolysosomal system via endosomes. Two-pore channels drive endolysosomal trafficking through the release of endolysosomal Ca2+. Recent evidence suggested that the pharmacological inhibition of TPCs prevents Ebola virus and Middle East Respiratory Syndrome COronaVirus (MERS-CoV) entry into host cells. In this perspective, we briefly summarize the biophysical and pharmacological features of TPCs, illustrate their emerging role in the cardiovascular system, and finally present them as a reliable target to treat cardiovascular complications in COVID-19 patients.
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Affiliation(s)
- Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | - Sharon Negri
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | - Pawan Faris
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | - Angelica Perna
- Department of Medicine and Health Sciences “V. Tiberio”, University of Molise, Campobasso, Italy
| | - Antonio De Luca
- Section of Human Anatomy, Department of Mental and Physical Health and Preventive Medicine, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Teresa Soda
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Roberto Berra-Romani
- School of Medicine, Department of Biomedicine, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Germano Guerra
- Department of Medicine and Health Sciences “V. Tiberio”, University of Molise, Campobasso, Italy
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26
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Saric A, Freeman SA. Endomembrane Tension and Trafficking. Front Cell Dev Biol 2021; 8:611326. [PMID: 33490077 PMCID: PMC7820182 DOI: 10.3389/fcell.2020.611326] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/09/2020] [Indexed: 12/11/2022] Open
Abstract
Eukaryotic cells employ diverse uptake mechanisms depending on their specialized functions. While such mechanisms vary widely in their defining criteria: scale, molecular machinery utilized, cargo selection, and cargo destination, to name a few, they all result in the internalization of extracellular solutes and fluid into membrane-bound endosomes. Upon scission from the plasma membrane, this compartment is immediately subjected to extensive remodeling which involves tubulation and vesiculation/budding of the limiting endomembrane. This is followed by a maturation process involving concomitant retrograde transport by microtubule-based motors and graded fusion with late endosomes and lysosomes, organelles that support the degradation of the internalized content. Here we review an important determinant for sorting and trafficking in early endosomes and in lysosomes; the control of tension on the endomembrane. Remodeling of endomembranes is opposed by high tension (caused by high hydrostatic pressure) and supported by the relief of tension. We describe how the timely and coordinated efflux of major solutes along the endocytic pathway affords the cell control over such tension. The channels and transporters that expel the smallest components of the ingested medium from the early endocytic fluid are described in detail as these systems are thought to enable endomembrane deformation by curvature-sensing/generating coat proteins. We also review similar considerations for the lysosome where resident hydrolases liberate building blocks from luminal macromolecules and transporters flux these organic solutes to orchestrate trafficking events. How the cell directs organellar trafficking based on the luminal contents of organelles of the endocytic pathway is not well-understood, however, we propose that the control over membrane tension by solute transport constitutes one means for this to ensue.
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Affiliation(s)
- Amra Saric
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Center for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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27
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Notomi T, Kise C, Kobayashi R, Otsuka M, Momota Y, Ezura Y, Kawazoe T. TPC1 and TPC2 Promote Osteoclastogenesis. J HARD TISSUE BIOL 2021. [DOI: 10.2485/jhtb.30.333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | - Chie Kise
- Department of Pharmacology, Osaka Dental University
| | | | - Miki Otsuka
- Department of Pharmacology, Osaka Dental University
| | | | - Yoichi Ezura
- Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University
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28
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Vassileva K, Marsh M, Patel S. Two-pore channels as master regulators of membrane trafficking and endocytic well-being. CURRENT OPINION IN PHYSIOLOGY 2020; 17:163-168. [PMID: 32838099 PMCID: PMC7426208 DOI: 10.1016/j.cophys.2020.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Two-pore channels (TPCs) are a ubiquitous class of Ca2+- and Na+-permeable ion channels expressed within the endo-lysosomal system. They have emerged as central regulators of a wide array of physiological processes intimately linked to information processing. In this short review, we highlight how molecular and chemical strategies have uncovered multiple roles for TPCs in regulating various aspects of endo-lysosomal trafficking associated with disease. We summarise advances in the identification of new small molecules to pharmacologically target TPCs for medical benefit. Lastly, we discuss possible underpinning molecular mechanism(s) that translate TPC-mediated ionic fluxes to function.
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Affiliation(s)
- Kristin Vassileva
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Mark Marsh
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, London, UK
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29
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Mallmann RT, Klugbauer N. Genetic Inactivation of Two-Pore Channel 1 Impairs Spatial Learning and Memory. Behav Genet 2020; 50:401-410. [PMID: 32889694 PMCID: PMC7581579 DOI: 10.1007/s10519-020-10011-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/28/2020] [Indexed: 12/16/2022]
Abstract
Two-pore channels (TPCs) constitute a small family of cation channels that are localized in membranes of endosomal and lysosomal compartments. Although their roles for vesicular fusion and endolysosomal trafficking have been investigated, our knowledge on their expression pattern and higher order functions in the murine brain is still limited. Western blot analysis indicated a broad expression of TPC1 in the neocortex, cerebellum and hippocampus. In order to investigate the consequences of the genetic inactivation of TPC1, we performed a set of behavioural studies with TPC1−/− mice. TPC1−/− mice were analysed for an altered motor coordination and grip-strength, exploratory drive and anxiety as well as learning and memory. TPC1−/− mice did not show any differences in their exploratory drive or in their anxiety levels. There were also no differences in spontaneous activity or motor performance. However, the Morris water maze test uncovered a deficit in spatial learning and memory in TPC1−/− mice.
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Affiliation(s)
- Robert Theodor Mallmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät, Albert-Ludwigs-Universität, Freiburg, Germany
| | - Norbert Klugbauer
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät, Albert-Ludwigs-Universität, Freiburg, Germany. .,Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät, Universität Freiburg, Albertstr. 25, 79104, Freiburg, Germany.
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30
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Božić M, Verkhratsky A, Zorec R, Stenovec M. Exocytosis of large-diameter lysosomes mediates interferon γ-induced relocation of MHC class II molecules toward the surface of astrocytes. Cell Mol Life Sci 2020; 77:3245-3264. [PMID: 31667557 PMCID: PMC7391398 DOI: 10.1007/s00018-019-03350-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 10/01/2019] [Accepted: 10/21/2019] [Indexed: 12/13/2022]
Abstract
Astrocytes are the key homeostatic cells in the central nervous system; initiation of reactive astrogliosis contributes to neuroinflammation. Pro-inflammatory cytokine interferon γ (IFNγ) induces the expression of the major histocompatibility complex class II (MHCII) molecules, involved in antigen presentation in reactive astrocytes. The pathway for MHCII delivery to the astrocyte plasma membrane, where MHCII present antigens, is unknown. Rat astrocytes in culture and in organotypic slices were exposed to IFNγ to induce reactive astrogliosis. Astrocytes were probed with optophysiologic tools to investigate subcellular localization of immunolabeled MHCII, and with electrophysiology to characterize interactions of single vesicles with the plasmalemma. In culture and in organotypic slices, IFNγ augmented the astrocytic expression of MHCII, which prominently co-localized with lysosomal marker LAMP1-EGFP, modestly co-localized with Rab7, and did not co-localize with endosomal markers Rab4A, EEA1, and TPC1. MHCII lysosomal localization was corroborated by treatment with the lysosomolytic agent glycyl-L-phenylalanine-β-naphthylamide, which reduced the number of MHCII-positive vesicles. The surface presence of MHCII was revealed by immunolabeling of live non-permeabilized cells. In IFNγ-treated astrocytes, an increased fraction of large-diameter exocytotic vesicles (lysosome-like vesicles) with prolonged fusion pore dwell time and larger pore conductance was recorded, whereas the rate of endocytosis was decreased. Stimulation with ATP, which triggers cytosolic calcium signaling, increased the frequency of exocytotic events, whereas the frequency of full endocytosis was further reduced. In IFNγ-treated astrocytes, MHCII-linked antigen surface presentation is mediated by increased lysosomal exocytosis, whereas surface retention of antigens is prolonged by concomitant inhibition of endocytosis.
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Affiliation(s)
- Mićo Božić
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia
| | - Alexei Verkhratsky
- Celica Biomedical, Tehnološki park 24, 1000, Ljubljana, Slovenia
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK
- Achucarro Center for Neuroscience, IKERBASQUE, 48011, Bilbao, Spain
| | - Robert Zorec
- Celica Biomedical, Tehnološki park 24, 1000, Ljubljana, Slovenia.
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia.
| | - Matjaž Stenovec
- Celica Biomedical, Tehnološki park 24, 1000, Ljubljana, Slovenia.
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia.
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31
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Arlt E, Fraticelli M, Tsvilovskyy V, Nadolni W, Breit A, O'Neill TJ, Resenberger S, Wennemuth G, Wahl-Schott C, Biel M, Grimm C, Freichel M, Gudermann T, Klugbauer N, Boekhoff I, Zierler S. TPC1 deficiency or blockade augments systemic anaphylaxis and mast cell activity. Proc Natl Acad Sci U S A 2020; 117:18068-18078. [PMID: 32661165 PMCID: PMC7395440 DOI: 10.1073/pnas.1920122117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mast cells and basophils are main drivers of allergic reactions and anaphylaxis, for which prevalence is rapidly increasing. Activation of these cells leads to a tightly controlled release of inflammatory mediators stored in secretory granules. The release of these granules is dependent on intracellular calcium (Ca2+) signals. Ca2+ release from endolysosomal compartments is mediated via intracellular cation channels, such as two-pore channel (TPC) proteins. Here, we uncover a mechanism for how TPC1 regulates Ca2+ homeostasis and exocytosis in mast cells in vivo and ex vivo. Notably, in vivo TPC1 deficiency in mice leads to enhanced passive systemic anaphylaxis, reflected by increased drop in body temperature, most likely due to accelerated histamine-induced vasodilation. Ex vivo, mast cell-mediated histamine release and degranulation was augmented upon TPC1 inhibition, although mast cell numbers and size were diminished. Our results indicate an essential role of TPC1 in endolysosomal Ca2+ uptake and filling of endoplasmic reticulum Ca2+ stores, thereby regulating exocytosis in mast cells. Thus, pharmacological modulation of TPC1 might blaze a trail to develop new drugs against mast cell-related diseases, including allergic hypersensitivity.
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Affiliation(s)
- Elisabeth Arlt
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany
| | - Marco Fraticelli
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany
| | | | - Wiebke Nadolni
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany
| | - Andreas Breit
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany
| | - Thomas J O'Neill
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany
| | - Stefanie Resenberger
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany
| | - Gunther Wennemuth
- Institute for Anatomy, University of Duisburg-Essen, 45147 Duisburg, Germany
| | | | - Martin Biel
- Department of Pharmacy, Ludwig-Maximilians-Universität München, 81377 München, Germany
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany
| | - Marc Freichel
- Institute of Pharmacology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany
| | - Norbert Klugbauer
- Institute for Experimental and Clinical Pharmacology and Toxicology, Medical Faculty, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
| | - Ingrid Boekhoff
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany;
| | - Susanna Zierler
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, 80336 München, Germany;
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32
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Gerndt S, Krogsaeter E, Patel S, Bracher F, Grimm C. Discovery of lipophilic two‐pore channel agonists. FEBS J 2020; 287:5284-5293. [DOI: 10.1111/febs.15432] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/14/2020] [Accepted: 05/27/2020] [Indexed: 11/27/2022]
Affiliation(s)
- Susanne Gerndt
- Department of Pharmacy – Center for Drug Research Ludwig‐Maximilians‐Universität Munich Germany
| | - Einar Krogsaeter
- Walther Straub Institute of Pharmacology and Toxicology Faculty of Medicine Ludwig‐Maximilians‐Universität Munich Germany
| | - Sandip Patel
- Department of Cell and Developmental Biology University College London London UK
| | - Franz Bracher
- Department of Pharmacy – Center for Drug Research Ludwig‐Maximilians‐Universität Munich Germany
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology Faculty of Medicine Ludwig‐Maximilians‐Universität Munich Germany
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33
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Grimm C, Tang R. Could an endo-lysosomal ion channel be the Achilles heel of SARS-CoV2? Cell Calcium 2020; 88:102212. [PMID: 32402856 PMCID: PMC7201244 DOI: 10.1016/j.ceca.2020.102212] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 04/24/2020] [Indexed: 01/09/2023]
Abstract
The ongoing SARS-CoV2 outbreak has developed into a global pandemic. Despite previous outbreaks of SARS-CoV and the related MERS-CoV in recent years, neither a vaccine nor any other medication for an effective treatment are currently available. Endo-lysosomal two-pore cation channels have now emerged as potential novel targets for SARS-CoV treatment.
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34
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Khan N, Halcrow PW, Lakpa KL, Afghah Z, Miller NM, Dowdy SF, Geiger JD, Chen X. Two-pore channels regulate Tat endolysosome escape and Tat-mediated HIV-1 LTR transactivation. FASEB J 2020; 34:4147-4162. [PMID: 31950548 PMCID: PMC7079041 DOI: 10.1096/fj.201902534r] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/10/2019] [Accepted: 01/02/2020] [Indexed: 12/25/2022]
Abstract
HIV-1 Tat is essential for HIV-1 replication and appears to play an important role in the pathogenesis of HIV-associated neurological complications. Secreted from infected or transfected cells, Tat has the extraordinary ability to cross the plasma membrane. In the brain, Tat can be taken up by CNS cells via receptor-mediated endocytosis. Following endocytosis and its internalization into endolysosomes, Tat must be released in order for it to activate the HIV-1 LTR promoter and facilitate HIV-1 viral replication in the nucleus. However, the underlying mechanisms whereby Tat escapes endolysosomes remain unclear. Because Tat disrupts intracellular calcium homeostasis, we investigated the involvement of calcium in Tat endolysosome escape and subsequent LTR transactivation. We demonstrated that chelating endolysosome calcium with high-affinity rhodamine-dextran or chelating cytosolic calcium with BAPTA-AM attenuated Tat endolysosome escape and LTR transactivation. Significantly, we demonstrated that pharmacologically blocking and knocking down the endolysosome-resident two-pore channels (TPCs) attenuated Tat endolysosome escape and LTR transactivation. This calcium-mediated effect appears to be selective for TPCs because knocking down TRPML1 calcium channels was without effect. Our findings suggest that calcium released from TPCs is involved in Tat endolysosome escape and subsequent LTR transactivation. TPCs might represent a novel therapeutic target against HIV-1 infection and HIV-associated neurological complications.
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Affiliation(s)
- Nabab Khan
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNDUSA
| | - Peter W. Halcrow
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNDUSA
| | - Koffi L. Lakpa
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNDUSA
| | - Zahra Afghah
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNDUSA
| | - Nicole M. Miller
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNDUSA
| | - Steven F. Dowdy
- Department of Cellular and Molecular MedicineUniversity of California San Diego (UCSD) School of MedicineLa JollaCAUSA
| | - Jonathan D. Geiger
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNDUSA
| | - Xuesong Chen
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNDUSA
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35
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Affiliation(s)
- Jason S. King
- Centre for Membrane Interactions and Dynamics, Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - Elizabeth Smythe
- Centre for Membrane Interactions and Dynamics, Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
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36
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Chao YK, Chang SY, Grimm C. Endo-Lysosomal Cation Channels and Infectious Diseases. Rev Physiol Biochem Pharmacol 2020; 185:259-276. [PMID: 32748124 DOI: 10.1007/112_2020_31] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Among the infectious diseases caused by pathogenic microorganisms such as bacteria, viruses, parasites, or fungi, the most prevalent ones today are malaria, tuberculosis, influenza, HIV/AIDS, Ebola, dengue fever, and methicillin-resistant Staphylococcus aureus (MRSA) infection, and most recently Covid-19 (SARS-CoV2). Others with a rather devastating history and high fatality rates such as plague, cholera, or typhus seem less threatening today but have not been eradicated, and with a declining efficacy of current antibiotics they ought to be watched carefully. Another emerging issue in this context is health-care associated infection. About 100,000 hospitalized patients in the USA ( www.cdc.gov ) and 33,000 in Europe ( https://www.ecdc.europa.eu ) die each year as a direct consequence of an infection caused by bacteria resistant to antibiotics. Among viral infections, influenza is responsible for about 3-5 million cases of severe illness, and about 250,000 to 500,000 deaths annually ( www.who.int ). About 37 million people are currently living with HIV infection and about one million die from it each year. Coronaviruses such as MERS-CoV, SARS-CoV, but in particular the recent outbreak of Covid-19 (caused by SARS-CoV2) have resulted in large numbers of infections worldwide with an estimated several hundred thousand deaths (anticipated fatality rate: <5%). With a comparatively low mortality rate dengue virus causes between 50 and 100 million infections every year, leading to 50,000 deaths. In contrast, Ebola virus is the causative agent for one of the deadliest viral diseases. The Ebola outbreak in West Africa in 2014 is considered the largest outbreak in history with more than 11,000 deaths. Many of the deadliest pathogens such as Ebola virus, influenza virus, mycobacterium tuberculosis, dengue virus, and cholera exploit the endo-lysosomal trafficking system of host cells for penetration into the cytosol and replication. Defects in endo-lysosomal maturation, trafficking, fusion, or pH homeostasis can efficiently reduce the cytotoxicity caused by these pathogens. Most of these functions critically depend on endo-lysosomal membrane proteins such as transporters and ion channels. In particular, cation channels such as the mucolipins (TRPMLs) or the two-pore channels (TPCs) are involved in all of these aspects of endo-lysosomal integrity. In this review we will discuss the correlations between pathogen toxicity and endo-lysosomal cation channel function, and their potential as drug targets for infectious disease therapy.
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Affiliation(s)
- Yu-Kai Chao
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich, Germany
| | - Sui-Yuan Chang
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan.,Department of Laboratory Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich, Germany.
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37
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Freeman SA, Uderhardt S, Saric A, Collins RF, Buckley CM, Mylvaganam S, Boroumand P, Plumb J, Germain RN, Ren D, Grinstein S. Lipid-gated monovalent ion fluxes regulate endocytic traffic and support immune surveillance. Science 2019; 367:301-305. [PMID: 31806695 DOI: 10.1126/science.aaw9544] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 10/08/2019] [Accepted: 11/25/2019] [Indexed: 12/21/2022]
Abstract
Despite ongoing (macro)pinocytosis of extracellular fluid, the volume of the endocytic pathway remains unchanged. To investigate the underlying mechanism, we used high-resolution video imaging to analyze the fate of macropinosomes formed by macrophages in vitro and in situ. Na+, the primary cationic osmolyte internalized, exited endocytic vacuoles via two-pore channels, accompanied by parallel efflux of Cl- and osmotically coupled water. The resulting shrinkage caused crenation of the membrane, which fostered recruitment of curvature-sensing proteins. These proteins stabilized tubules and promoted their elongation, driving vacuolar remodeling, receptor recycling, and resolution of the organelles. Failure to resolve internalized fluid impairs the tissue surveillance activity of resident macrophages. Thus, osmotically driven increases in the surface-to-volume ratio of endomembranes promote traffic between compartments and help to ensure tissue homeostasis.
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Affiliation(s)
- Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.
| | - Stefan Uderhardt
- Lymphocyte Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.,Department of Internal Medicine 3 - Rheumatology and Immunology, Universitätsklinikum Erlangen and Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Amra Saric
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Richard F Collins
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Catherine M Buckley
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Sivakami Mylvaganam
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Parastoo Boroumand
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Jonathan Plumb
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Ronald N Germain
- Lymphocyte Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Dejian Ren
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada. .,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
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38
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Krogsaeter EK, Biel M, Wahl-Schott C, Grimm C. The protein interaction networks of mucolipins and two-pore channels. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2019; 1866:1111-1123. [PMID: 30395881 PMCID: PMC7111325 DOI: 10.1016/j.bbamcr.2018.10.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/24/2018] [Accepted: 10/26/2018] [Indexed: 12/11/2022]
Abstract
BACKGROUND The endolysosomal, non-selective cation channels, two-pore channels (TPCs) and mucolipins (TRPMLs), regulate intracellular membrane dynamics and autophagy. While partially compensatory for each other, isoform-specific intracellular distribution, cell-type expression patterns, and regulatory mechanisms suggest different channel isoforms confer distinct properties to the cell. SCOPE OF REVIEW Briefly, established TPC/TRPML functions and interaction partners ('interactomes') are discussed. Novel TRPML3 interactors are shown, and a meta-analysis of experimentally obtained channel interactomes conducted. Accordingly, interactomes are compared and contrasted, and subsequently described in detail for TPC1, TPC2, TRPML1, and TRPML3. MAJOR CONCLUSIONS TPC interactomes are well-defined, encompassing intracellular membrane organisation proteins. TRPML interactomes are varied, encompassing cardiac contractility- and chaperone-mediated autophagy proteins, alongside regulators of intercellular signalling. GENERAL SIGNIFICANCE Comprising recently proposed targets to treat cancers, infections, metabolic disease and neurodegeneration, the advancement of TPC/TRPML understanding is of considerable importance. This review proposes novel directions elucidating TPC/TRPML relevance in health and disease. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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Affiliation(s)
- Einar K Krogsaeter
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Munich (LMU) Nussbaumstrasse 26, 80336 Munich
| | - Martin Biel
- Department of Pharmacy - Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Germany
| | - Christian Wahl-Schott
- Hannover Medical School, Institute for Neurophysiology, OE 4230, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Christian Grimm
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Munich (LMU) Nussbaumstrasse 26, 80336 Munich.
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Levanova N, Mattheis C, Carson D, To KN, Jank T, Frankel G, Aktories K, Schroeder GN. The Legionella effector LtpM is a new type of phosphoinositide-activated glucosyltransferase. J Biol Chem 2019; 294:2862-2879. [PMID: 30573678 PMCID: PMC6393602 DOI: 10.1074/jbc.ra118.005952] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 12/13/2018] [Indexed: 01/01/2023] Open
Abstract
Legionella pneumophila causes Legionnaires' disease, a severe form of pneumonia. L. pneumophila translocates more than 300 effectors into host cells via its Dot/Icm (Defective in organelle trafficking/Intracellular multiplication) type IV secretion system to enable its replication in target cells. Here, we studied the effector LtpM, which is encoded in a recombination hot spot in L. pneumophila Paris. We show that a C-terminal phosphoinositol 3-phosphate (PI3P)-binding domain, also found in otherwise unrelated effectors, targets LtpM to the Legionella-containing vacuole and to early and late endosomes. LtpM expression in yeast caused cytotoxicity. Sequence comparison and structural homology modeling of the N-terminal domain of LtpM uncovered a remote similarity to the glycosyltransferase (GT) toxin PaTox from the bacterium Photorhabdus asymbiotica; however, instead of the canonical DxD motif of GT-A type glycosyltransferases, essential for enzyme activity and divalent cation coordination, we found that a DxN motif is present in LtpM. Using UDP-glucose as sugar donor, we show that purified LtpM nevertheless exhibits glucohydrolase and autoglucosylation activity in vitro and demonstrate that PI3P binding activates LtpM's glucosyltransferase activity toward protein substrates. Substitution of the aspartate or the asparagine in the DxN motif abolished the activity of LtpM. Moreover, whereas all glycosyltransferase toxins and effectors identified so far depend on the presence of divalent cations, LtpM is active in their absence. Proteins containing LtpM-like GT domains are encoded in the genomes of other L. pneumophila isolates and species, suggesting that LtpM is the first member of a novel family of glycosyltransferase effectors employed to subvert hosts.
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Affiliation(s)
- Nadezhda Levanova
- From the Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany
| | - Corinna Mattheis
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
| | - Danielle Carson
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
| | - Ka-Ning To
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
| | - Thomas Jank
- From the Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany
| | - Gad Frankel
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
| | - Klaus Aktories
- From the Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany,
| | - Gunnar Neels Schroeder
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
- the Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry, and Biomedical Sciences, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, United Kingdom
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Two-pore channels and disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1678-1686. [PMID: 29746898 PMCID: PMC6162333 DOI: 10.1016/j.bbamcr.2018.05.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 05/03/2018] [Indexed: 01/25/2023]
Abstract
Two-pore channels (TPCs) are Ca2+-permeable endo-lysosomal ion channels subject to multi-modal regulation. They mediate their physiological effects through releasing Ca2+ from acidic organelles in response to cues such as the second messenger, NAADP. Here, we review emerging evidence linking TPCs to disease. We discuss how perturbing both local and global Ca2+ changes mediated by TPCs through chemical and/or molecular manipulations can induce or reverse disease phenotypes. We cover evidence from models of Parkinson's disease, non-alcoholic fatty liver disease, Ebola infection, cancer, cardiac dysfunction and diabetes. A need for more drugs targeting TPCs is identified.
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Sterea AM, Almasi S, El Hiani Y. The hidden potential of lysosomal ion channels: A new era of oncogenes. Cell Calcium 2018; 72:91-103. [PMID: 29748137 DOI: 10.1016/j.ceca.2018.02.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 02/28/2018] [Accepted: 02/28/2018] [Indexed: 01/14/2023]
Abstract
Lysosomes serve as the control centre for cellular clearance. These membrane-bound organelles receive biomolecules destined for degradation from intracellular and extracellular pathways; thus, facilitating the production of energy and shaping the fate of the cell. At the base of their functionality are the lysosomal ion channels which mediate the function of the lysosome through the modulation of ion influx and efflux. Ion channels form pores in the membrane of lysosomes and allow the passage of ions, a seemingly simple task which harbours the potential of overthrowing the cell's stability. Considered the master regulators of ion homeostasis, these integral membrane proteins enable the proper operation of the lysosome. Defects in the structure or function of these ion channels lead to the development of lysosomal storage diseases, neurodegenerative diseases and cancer. Although more than 50 years have passed since their discovery, lysosomes are not yet fully understood, with their ion channels being even less well characterized. However, significant improvements have been made in the development of drugs targeted against these ion channels as a means of combating diseases. In this review, we will examine how Ca2+, K+, Na+ and Cl- ion channels affect the function of the lysosome, their involvement in hereditary and spontaneous diseases, and current ion channel-based therapies.
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Affiliation(s)
- Andra M Sterea
- Departments of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Shekoufeh Almasi
- Departments of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Yassine El Hiani
- Departments of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.
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