101
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Grimm C, Chen CC, Wahl-Schott C, Biel M. Two-Pore Channels: Catalyzers of Endolysosomal Transport and Function. Front Pharmacol 2017; 8:45. [PMID: 28223936 PMCID: PMC5293812 DOI: 10.3389/fphar.2017.00045] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 01/20/2017] [Indexed: 01/17/2023] Open
Abstract
Two-pore channels (TPCs) have recently emerged as a novel class of non-selective cation channels in the endolysosomal system. There are two members in the human genome, TPC1 and TPC2. Studies with TPC knockout and knockdown models have revealed that these channels participate in the regulation of multiple endolysosomal trafficking pathways which when dysregulated can lead to or influence the development of a range of different diseases such as lysosomal storage, metabolic, or infectious diseases. TPCs have been demonstrated to be activated by different endogenous stimuli, PI(3,5)P2 and NAADP, and ATP has been found to block TPC activation via mTOR. Loss of TPCs can lead to obesity and hypercholesterolemia, and to a slow-down of intracellular virus and bacterial toxin trafficking, it can affect VEGF-induced neoangiogenesis, autophagy, human hair pigmentation or the acrosome reaction in sperm. Moreover, physiological roles of TPCs in cardiac myocytes and pancreatic β cells have been postulated.
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Affiliation(s)
- Christian Grimm
- Center for Integrated Protein Science Munich, Ludwig Maximilian University of MunichMunich, Germany
- Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of MunichMunich, Germany
| | - Cheng-Chang Chen
- Center for Integrated Protein Science Munich, Ludwig Maximilian University of MunichMunich, Germany
- Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of MunichMunich, Germany
| | - Christian Wahl-Schott
- Center for Integrated Protein Science Munich, Ludwig Maximilian University of MunichMunich, Germany
- Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of MunichMunich, Germany
| | - Martin Biel
- Center for Integrated Protein Science Munich, Ludwig Maximilian University of MunichMunich, Germany
- Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of MunichMunich, Germany
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102
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Nguyen ONP, Grimm C, Schneider LS, Chao YK, Atzberger C, Bartel K, Watermann A, Ulrich M, Mayr D, Wahl-Schott C, Biel M, Vollmar AM. Two-Pore Channel Function Is Crucial for the Migration of Invasive Cancer Cells. Cancer Res 2017; 77:1427-1438. [PMID: 28108508 DOI: 10.1158/0008-5472.can-16-0852] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 12/22/2016] [Accepted: 12/22/2016] [Indexed: 11/16/2022]
Abstract
Metastatic invasion is the major cause of cancer-related deaths. In this study, we introduce two-pore channels (TPC), a recently described class of NAADP- and PI(3,5)P2-sensitive Ca2+-permeable cation channels in the endolysosomal system of cells, as candidate targets for the treatment of invasive cancers. Inhibition of the channel abrogated migration of metastatic cancer cells in vitro Silencing or pharmacologic inhibition of the two-pore channel TPC2 reduced lung metastasis of mammary mouse cancer cells. Disrupting TPC function halted trafficking of β1-integrin, leading to its accumulation in EEA1-positive early endosomes. As a consequence, invasive cancer cells were no longer able to form leading edges, which are required for adequate migration. Our findings link TPC to cancer cell migration and provide a preclinical proof of concept for their candidacy as targets to treat metastatic cancers. Cancer Res; 77(6); 1427-38. ©2017 AACR.
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Affiliation(s)
- Ong Nam Phuong Nguyen
- Department of Pharmacy, Pharmaceutical Biology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Christian Grimm
- Department of Pharmacy, Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-University Munich, Munich, Germany
| | - Lina S Schneider
- Department of Pharmacy, Pharmaceutical Biology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Yu-Kai Chao
- Department of Pharmacy, Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-University Munich, Munich, Germany
| | - Carina Atzberger
- Department of Pharmacy, Pharmaceutical Biology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Karin Bartel
- Department of Pharmacy, Pharmaceutical Biology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Anna Watermann
- Department of Pharmacy, Pharmaceutical Biology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Melanie Ulrich
- Department of Pharmacy, Pharmaceutical Biology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Doris Mayr
- Pathological Institute, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Christian Wahl-Schott
- Department of Pharmacy, Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-University Munich, Munich, Germany
| | - Martin Biel
- Department of Pharmacy, Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-University Munich, Munich, Germany.
| | - Angelika M Vollmar
- Department of Pharmacy, Pharmaceutical Biology, Ludwig-Maximilians-University Munich, Munich, Germany.
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103
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Abstract
Organellar two-pore channels (TPCs) contain two copies of a Shaker-like six-transmembrane (6-TM) domain in each subunit and are ubiquitously expressed in plants and animals. Interestingly, plant and animal TPCs share high sequence similarity in the filter region, yet exhibit drastically different ion selectivity. Plant TPC1 functions as a nonselective cation channel on the vacuole membrane, whereas mammalian TPC channels have been shown to be endo/lysosomal Na+-selective or Ca2+-release channels. In this study, we performed systematic characterization of the ion selectivity of TPC1 from Arabidopsis thaliana (AtTPC1) and compared its selectivity with the selectivity of human TPC2 (HsTPC2). We demonstrate that AtTPC1 is selective for Ca2+ over Na+, but nonselective among monovalent cations (Li+, Na+, and K+). Our results also confirm that HsTPC2 is a Na+-selective channel activated by phosphatidylinositol 3,5-bisphosphate. Guided by our recent structure of AtTPC1, we converted AtTPC1 to a Na+-selective channel by mimicking the selectivity filter of HsTPC2 and identified key residues in the TPC filters that differentiate the selectivity between AtTPC1 and HsTPC2. Furthermore, the structure of the Na+-selective AtTPC1 mutant elucidates the structural basis for Na+ selectivity in mammalian TPCs.
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104
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High resolution structural evidence suggests the Sarcoplasmic Reticulum forms microdomains with Acidic Stores (lysosomes) in the heart. Sci Rep 2017; 7:40620. [PMID: 28094777 PMCID: PMC5240626 DOI: 10.1038/srep40620] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 12/09/2016] [Indexed: 01/10/2023] Open
Abstract
Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) stimulates calcium release from acidic stores such as lysosomes and is a highly potent calcium-mobilising second messenger. NAADP plays an important role in calcium signalling in the heart under basal conditions and following β-adrenergic stress. Nevertheless, the spatial interaction of acidic stores with other parts of the calcium signalling apparatus in cardiac myocytes is unknown. We present evidence that lysosomes are intimately associated with the sarcoplasmic reticulum (SR) in ventricular myocytes; a median separation of 20 nm in 2D electron microscopy and 3.3 nm in 3D electron tomography indicates a genuine signalling microdomain between these organelles. Fourier analysis of immunolabelled lysosomes suggests a sarcomeric pattern (dominant wavelength 1.80 μm). Furthermore, we show that lysosomes form close associations with mitochondria (median separation 6.2 nm in 3D studies) which may provide a basis for the recently-discovered role of NAADP in reperfusion-induced cell death. The trigger hypothesis for NAADP action proposes that calcium release from acidic stores subsequently acts to enhance calcium release from the SR. This work provides structural evidence in cardiac myocytes to indicate the formation of microdomains between acidic and SR calcium stores, supporting emerging interpretations of NAADP physiology and pharmacology in heart.
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105
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Penny CJ, Rahman T, Sula A, Miles AJ, Wallace BA, Patel S. Isolated pores dissected from human two-pore channel 2 are functional. Sci Rep 2016; 6:38426. [PMID: 27941820 PMCID: PMC5150636 DOI: 10.1038/srep38426] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 11/08/2016] [Indexed: 01/30/2023] Open
Abstract
Multi-domain voltage-gated ion channels appear to have evolved through sequential rounds of intragenic duplication from a primordial one-domain precursor. Whereas modularity within one-domain symmetrical channels is established, little is known about the roles of individual regions within more complex asymmetrical channels where the domains have undergone substantial divergence. Here we isolated and characterised both of the divergent pore regions from human TPC2, a two-domain channel that holds a key intermediate position in the evolution of voltage-gated ion channels. In HeLa cells, each pore localised to the ER and caused Ca2+ depletion, whereas an ER-targeted pore mutated at a residue that inactivates full-length TPC2 did not. Additionally, one of the pores expressed at high levels in E. coli. When purified, it formed a stable, folded tetramer. Liposomes reconstituted with the pore supported Ca2+ and Na+ uptake that was inhibited by known blockers of full-length channels. Computational modelling of the pore corroborated cationic permeability and drug interaction. Therefore, despite divergence, both pores are constitutively active in the absence of their partners and retain several properties of the wild-type pore. Such symmetrical ‘pore-only’ proteins derived from divergent channel domains may therefore provide tractable tools for probing the functional architecture of complex ion channels.
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Affiliation(s)
- Christopher J Penny
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK.,Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, WC1E 7HX, UK
| | - Taufiq Rahman
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD, UK
| | - Altin Sula
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, WC1E 7HX, UK
| | - Andrew J Miles
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, WC1E 7HX, UK
| | - B A Wallace
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, WC1E 7HX, UK
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK
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106
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Evans AM. Nanojunctions of the Sarcoplasmic Reticulum Deliver Site- and Function-Specific Calcium Signaling in Vascular Smooth Muscles. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:1-47. [PMID: 28212795 DOI: 10.1016/bs.apha.2016.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Vasoactive agents may induce myocyte contraction, dilation, and the switch from a contractile to a migratory-proliferative phenotype(s), which requires changes in gene expression. These processes are directed, in part, by Ca2+ signals, but how different Ca2+ signals are generated to select each function is enigmatic. We have previously proposed that the strategic positioning of Ca2+ pumps and release channels at membrane-membrane junctions of the sarcoplasmic reticulum (SR) demarcates cytoplasmic nanodomains, within which site- and function-specific Ca2+ signals arise. This chapter will describe how nanojunctions of the SR may: (1) define cytoplasmic nanospaces about the plasma membrane, mitochondria, contractile myofilaments, lysosomes, and the nucleus; (2) provide for functional segregation by restricting passive diffusion and by coordinating active ion transfer within a given nanospace via resident Ca2+ pumps and release channels; (3) select for contraction, relaxation, and/or changes in gene expression; and (4) facilitate the switch in myocyte phenotype through junctional reorganization. This should serve to highlight the need for further exploration of cellular nanojunctions and the mechanisms by which they operate, that will undoubtedly open up new therapeutic horizons.
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Affiliation(s)
- A M Evans
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom.
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107
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García-Rúa V, Feijóo-Bandín S, García-Vence M, Aragón-Herrera A, Bravo SB, Rodríguez-Penas D, Mosquera-Leal A, Lear PV, Parrington J, Alonso J, Roselló-Lletí E, Portolés M, Rivera M, González-Juanatey JR, Lago F. Metabolic alterations derived from absence of Two-Pore Channel 1 at cardiac level. J Biosci 2016; 41:643-658. [DOI: 10.1007/s12038-016-9647-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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108
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Enrich C, Rentero C, Grewal T. Annexin A6 in the liver: From the endocytic compartment to cellular physiology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:933-946. [PMID: 27984093 DOI: 10.1016/j.bbamcr.2016.10.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 10/25/2016] [Accepted: 10/26/2016] [Indexed: 12/15/2022]
Abstract
Annexin A6 (AnxA6) belongs to the conserved annexin family - a group of Ca2+-dependent membrane binding proteins. AnxA6 is the largest of all annexins and highly expressed in smooth muscle, hepatocytes, endothelial cells and cardiomyocytes. Upon activation, AnxA6 binds to negatively charged phospholipids in a wide range of intracellular localizations, in particular the plasma membrane, late endosomes/pre-lysosomes, but also synaptic vesicles and sarcolemma. In these cellular sites, AnxA6 is believed to contribute to the organization of membrane microdomains, such as cholesterol-rich lipid rafts and confer multiple regulatory functions, ranging from vesicle fusion, endocytosis and exocytosis to programmed cell death and muscle contraction. Growing evidence supports that Ca2+ and Ca2+-binding proteins control endocytosis and autophagy. Their regulatory role seems to operate at the level of the signalling pathways that initiate autophagy or at later stages, when autophagosomes fuse with endolysosomal compartments. The convergence of the autophagic and endocytic vesicles to lysosomes shares several features that depend on Ca2+ originating from lysosomes/late endosomes and seems to depend on proteins that are subsequently activated by this cation. However, the involvement of Ca2+ and its effector proteins in these autophagic and endocytic stages still remains poorly understood. Although AnxA6 makes up almost 0.25% of total protein in the liver, little is known about its function in hepatocytes. Within the endocytic route, we identified AnxA6 in endosomes and autophagosomes of hepatocytes. Hence, AnxA6 and possibly other annexins might represent new Ca2+ effectors that regulate converging steps of autophagy and endocytic trafficking in hepatocytes. 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)
- Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cellular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain.
| | - Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cellular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Thomas Grewal
- Faculty of Pharmacy A15, University of Sydney, Sydney, NSW 2006, Australia
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109
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Brailoiu GC, Brailoiu E. Modulation of Calcium Entry by the Endo-lysosomal System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:423-47. [PMID: 27161239 DOI: 10.1007/978-3-319-26974-0_18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Endo-lysosomes are acidic organelles that besides the role in macromolecules degradation, act as intracellular Ca(2+) stores. Nicotinic acid adenine dinucleotide phosphate (NAADP), the most potent Ca(2+)-mobilizing second messenger, produced in response to agonist stimulation, activates Ca(2+)-releasing channels on endo-lysosomes and modulates a variety of cellular functions. NAADP-evoked signals are amplified by Ca(2+) release from endoplasmic reticulum, via the recruitment of inositol 1,4,5-trisphosphate and/or ryanodine receptors through a Ca(2+)-induced Ca(2+)- release (CICR) mechanism. The endo-lysosomal Ca(2+) channels activated by NAADP were recently identified as the two-pore channels (TPCs). In addition to TPCs, endo-lysosomes express another distinct family of Ca(2+)- permeable channels, namely the transient receptor potential mucolipin (TRPML) channels, functionally distinct from TPCs. TPCs belong to the voltage-gated channels, resembling voltage-gated Na(+) and Ca(2+) channels. TPCs have important roles in vesicular fusion and trafficking, in triggering a global Ca(2+) signal and in modulation of the membrane excitability. Depletion of acidic Ca(2+) stores has been shown to activate store-operated Ca(2+) entry in human platelets and mouse pancreatic β-cells. In human platelets, Ca(2+) influx in response to acidic stores depletion is facilitated by the tubulin-cytoskeleton and occurs through non-selective cation channels and transient receptor potential canonical (TRPC) channels. Emerging evidence indicates that activation of intracellular receptors, situated on endo-lysosomes, elicits canonical and non-canonical signaling mechanisms that involve CICR and activation of non-selective cation channels in plasma membrane. The ability of endo-lysosomal Ca(2+) stores to modulate the Ca(2+) release from other organelles and the Ca(2+) entry increases the diversity and complexity of cellular signaling mechanisms.
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Affiliation(s)
- G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Jefferson School of Pharmacy, Thomas Jefferson University, 901 Walnut St, Rm 916, Philadelphia, PA, 19107, USA.
| | - Eugen Brailoiu
- Center for Substance Abuse Research, Temple University School of Medicine, 3500 N. Broad Street, Room 848, Philadelphia, PA, 19140, USA
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110
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Imbery JF, Bhattacharya S, Khuder S, Weiss A, Goswamee P, Iqbal AK, Giovannucci DR. cAMP-dependent recruitment of acidic organelles for Ca2+ signaling in the salivary gland. Am J Physiol Cell Physiol 2016; 311:C697-C709. [PMID: 27605449 DOI: 10.1152/ajpcell.00010.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 08/29/2016] [Indexed: 12/29/2022]
Abstract
Autonomic neural activation of intracellular Ca2+ release in parotid acinar cells induces the secretion of the fluid and protein components of primary saliva critical for maintaining overall oral homeostasis. In the current study, we profiled the role of acidic organelles in shaping the Ca2+ signals of parotid acini using a variety of imaging and pharmacological approaches. Results demonstrate that zymogen granules predominate as an apically polarized population of acidic organelles that contributes to the initial Ca2+ release. Moreover, we provide evidence that indicates a role for the intracellular messenger NAADP in the release of Ca2+ from acidic organelles following elevation of cAMP. Our data are consistent with the "trigger" hypothesis where localized release of Ca2+ sensitizes canonical intracellular Ca2+ channels to enhance signals from the endoplasmic reticulum. Release from acidic stores may be important for initiating saliva secretion at low levels of stimulation and a potential therapeutic target to augment secretory activity in hypofunctioning salivary glands.
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Affiliation(s)
- John F Imbery
- Department of Neurosciences, University of Toledo Medical Center, Toledo, Ohio
| | - Sumit Bhattacharya
- Department of Neurosciences, University of Toledo Medical Center, Toledo, Ohio
| | - Sura Khuder
- Department of Neurosciences, University of Toledo Medical Center, Toledo, Ohio
| | - Amanda Weiss
- Department of Neurosciences, University of Toledo Medical Center, Toledo, Ohio
| | | | - Azwar K Iqbal
- Department of Neurosciences, University of Toledo Medical Center, Toledo, Ohio
| | - David R Giovannucci
- Department of Neurosciences, University of Toledo Medical Center, Toledo, Ohio
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111
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Fernández B, Fdez E, Gómez-Suaga P, Gil F, Molina-Villalba I, Ferrer I, Patel S, Churchill GC, Hilfiker S. Iron overload causes endolysosomal deficits modulated by NAADP-regulated 2-pore channels and RAB7A. Autophagy 2016; 12:1487-506. [PMID: 27383256 PMCID: PMC5082776 DOI: 10.1080/15548627.2016.1190072] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 05/05/2016] [Accepted: 05/11/2016] [Indexed: 12/19/2022] Open
Abstract
Various neurodegenerative disorders are associated with increased brain iron content. Iron is known to cause oxidative stress, which concomitantly promotes cell death. Whereas endolysosomes are known to serve as intracellular iron storage organelles, the consequences of increased iron on endolysosomal functioning, and effects on cell viability upon modulation of endolysosomal iron release remain largely unknown. Here, we show that increasing intracellular iron causes endolysosomal alterations associated with impaired autophagic clearance of intracellular protein aggregates, increased cytosolic oxidative stress and increased cell death. These effects are subject to regulation by NAADP, a potent second messenger reported to target endolysosomal TPCNs (2-pore channels). Consistent with endolysosomal iron storage, cytosolic iron levels are modulated by NAADP, and increased cytosolic iron is detected when overexpressing active, but not inactive TPCNs, indicating that these channels can modulate endolysosomal iron release. Cell death triggered by altered intralysosomal iron handling is abrogated in the presence of an NAADP antagonist or when inhibiting RAB7A activity. Taken together, our results suggest that increased endolysosomal iron causes cell death associated with increased cytosolic oxidative stress as well as autophagic impairments, and these effects are subject to modulation by endolysosomal ion channel activity in a RAB7A-dependent manner. These data highlight alternative therapeutic strategies for neurodegenerative disorders associated with increased intracellular iron load.
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Affiliation(s)
- Belén Fernández
- Institute of Parasitology and Biomedicine “López-Neyra,” Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Elena Fdez
- Institute of Parasitology and Biomedicine “López-Neyra,” Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Patricia Gómez-Suaga
- Institute of Parasitology and Biomedicine “López-Neyra,” Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Fernando Gil
- Department of Legal Medicine and Toxicology, School of Medicine, University of Granada, Granada, Spain
| | - Isabel Molina-Villalba
- Department of Legal Medicine and Toxicology, School of Medicine, University of Granada, Granada, Spain
| | - Isidro Ferrer
- Institute of Neuropathology, IDIBELL-University Hospital Bellvitge, University of Barcelona, Llobregat, Spain
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, London, UK
| | | | - Sabine Hilfiker
- Institute of Parasitology and Biomedicine “López-Neyra,” Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
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112
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Feijóo-Bandín S, García-Vence M, García-Rúa V, Roselló-Lletí E, Portolés M, Rivera M, González-Juanatey JR, Lago F. Two-pore channels (TPCs): Novel voltage-gated ion channels with pleiotropic functions. Channels (Austin) 2016; 11:20-33. [PMID: 27440385 DOI: 10.1080/19336950.2016.1213929] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Two-pore channels (TPC1-3) comprise a subfamily of the eukaryotic voltage-gated ion channels (VGICs) superfamily that are mainly expressed in acidic stores in plants and animals. TPCS are widespread across the animal kingdom, with primates, mice and rats lacking TPC3, and mainly act as Ca+ and Na+ channels, although it was also suggested that they could be permeable to other ions. Nowadays, TPCs have been related to the development of different diseases, including Parkinson´s disease, obesity or myocardial ischemia. Due to this, their study has raised the interest of the scientific community to try to understand their mechanism of action in order to be able to develop an efficient drug that could regulate TPCs activity. In this review, we will provide an updated view regarding TPCs structure, function and activation, as well as their role in different pathophysiological processes.
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Affiliation(s)
- Sandra Feijóo-Bandín
- a Cellular and Molecular Cardiology Research Unit and Department of Cardiology , Institute of Biomedical Research and University Clinical Hospital , Santiago de Compostela , Spain
| | - María García-Vence
- a Cellular and Molecular Cardiology Research Unit and Department of Cardiology , Institute of Biomedical Research and University Clinical Hospital , Santiago de Compostela , Spain
| | - Vanessa García-Rúa
- a Cellular and Molecular Cardiology Research Unit and Department of Cardiology , Institute of Biomedical Research and University Clinical Hospital , Santiago de Compostela , Spain
| | - Esther Roselló-Lletí
- b Cardiocirculatory Unit, Health Institute of La Fe University Hospital , Valencia , Spain
| | - Manuel Portolés
- b Cardiocirculatory Unit, Health Institute of La Fe University Hospital , Valencia , Spain
| | - Miguel Rivera
- b Cardiocirculatory Unit, Health Institute of La Fe University Hospital , Valencia , Spain
| | - José Ramón González-Juanatey
- a Cellular and Molecular Cardiology Research Unit and Department of Cardiology , Institute of Biomedical Research and University Clinical Hospital , Santiago de Compostela , Spain
| | - Francisca Lago
- a Cellular and Molecular Cardiology Research Unit and Department of Cardiology , Institute of Biomedical Research and University Clinical Hospital , Santiago de Compostela , Spain
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113
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Regulation of lysosomal ion homeostasis by channels and transporters. SCIENCE CHINA-LIFE SCIENCES 2016; 59:777-91. [PMID: 27430889 PMCID: PMC5147046 DOI: 10.1007/s11427-016-5090-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/02/2016] [Indexed: 02/05/2023]
Abstract
Lysosomes are the major organelles that carry out degradation functions. They integrate and digest materials compartmentalized by endocytosis, phagocytosis or autophagy. In addition to more than 60 hydrolases residing in the lysosomes, there are also ion channels and transporters that mediate the flux or transport of H+, Ca2+, Na+, K+, and Cl− across the lysosomal membranes. Defects in ionic exchange can lead to abnormal lysosome morphology, defective vesicle trafficking, impaired autophagy, and diseases such as neurodegeneration and lysosomal storage disorders. The latter are characterized by incomplete lysosomal digestion and accumulation of toxic materials inside enlarged intracellular vacuoles. In addition to degradation, recent studies have revealed the roles of lysosomes in metabolic pathways through kinases such as mechanistic target of rapamycin (mTOR) and transcriptional regulation through calcium signaling molecules such as transcription factor EB (TFEB) and calcineurin. Owing to the development of new approaches including genetically encoded fluorescence probes and whole endolysosomal patch clamp recording techniques, studies on lysosomal ion channels have made remarkable progress in recent years. In this review, we will focus on the current knowledge of lysosome-resident ion channels and transporters, discuss their roles in maintaining lysosomal function, and evaluate how their dysfunction can result in disease.
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114
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From contraction to gene expression: nanojunctions of the sarco/endoplasmic reticulum deliver site- and function-specific calcium signals. SCIENCE CHINA-LIFE SCIENCES 2016; 59:749-63. [PMID: 27376531 DOI: 10.1007/s11427-016-5071-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 04/07/2016] [Indexed: 10/21/2022]
Abstract
Calcium signals determine, for example, smooth muscle contraction and changes in gene expression. How calcium signals select for these processes is enigmatic. We build on the "panjunctional sarcoplasmic reticulum" hypothesis, describing our view that different calcium pumps and release channels, with different kinetics and affinities for calcium, are strategically positioned within nanojunctions of the SR and help demarcate their respective cytoplasmic nanodomains. SERCA2b and RyR1 are preferentially targeted to the sarcoplasmic reticulum (SR) proximal to the plasma membrane (PM), i.e., to the superficial buffer barrier formed by PM-SR nanojunctions, and support vasodilation. In marked contrast, SERCA2a may be entirely restricted to the deep, perinuclear SR and may supply calcium to this sub-compartment in support of vasoconstriction. RyR3 is also preferentially targeted to the perinuclear SR, where its clusters associate with lysosome-SR nanojunctions. The distribution of RyR2 is more widespread and extends from this region to the wider cell. Therefore, perinuclear RyR3s most likely support the initiation of global calcium waves at L-SR junctions, which subsequently propagate by calcium-induced calcium release via RyR2 in order to elicit contraction. Data also suggest that unique SERCA and RyR are preferentially targeted to invaginations of the nuclear membrane. Site- and function-specific calcium signals may thus arise to modulate stimulus-response coupling and transcriptional cascades.
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115
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Larisch N, Kirsch SA, Schambony A, Studtrucker T, Böckmann RA, Dietrich P. The function of the two-pore channel TPC1 depends on dimerization of its carboxy-terminal helix. Cell Mol Life Sci 2016; 73:2565-81. [PMID: 26781468 PMCID: PMC4894940 DOI: 10.1007/s00018-016-2131-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 12/07/2015] [Accepted: 01/04/2016] [Indexed: 12/12/2022]
Abstract
Two-pore channels (TPCs) constitute a family of intracellular cation channels with diverse permeation properties and functions in animals and plants. In the model plant Arabidopsis, the vacuolar cation channel TPC1 is involved in propagation of calcium waves and in cation homeostasis. Here, we discovered that the dimerization of a predicted helix within the carboxyl-terminus (CTH) is essential for the activity of TPC1. Bimolecular fluorescence complementation and co-immunoprecipitation demonstrated the interaction of the two C-termini and pointed towards the involvement of the CTH in this process. Synthetic CTH peptides dimerized with a dissociation constant of 3.9 µM. Disruption of this domain in TPC1 either by deletion or point mutations impeded the dimerization and cation transport. The homo-dimerization of the CTH was analyzed in silico using coarse-grained molecular dynamics (MD) simulations for the study of aggregation, followed by atomistic MD simulations. The simulations revealed that the helical region of the wild type, but not a mutated CTH forms a highly stable, antiparallel dimer with characteristics of a coiled-coil. We propose that the voltage- and Ca(2+)-sensitive conformation of TPC1 depends on C-terminal dimerization, adding an additional layer to the complex regulation of two-pore cation channels.
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Affiliation(s)
- Nina Larisch
- Molecular Plant Physiology, Department of Biology, University of Erlangen-Nürnberg, Staudtstrasse 5, 91058, Erlangen, Germany
| | - Sonja A Kirsch
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Staudtstrasse 5, 91058, Erlangen, Germany
| | - Alexandra Schambony
- Developmental Biology, Department of Biology, University of Erlangen-Nürnberg, Staudtstrasse 5, 91058, Erlangen, Germany
| | - Tanja Studtrucker
- Molecular Plant Physiology, Department of Biology, University of Erlangen-Nürnberg, Staudtstrasse 5, 91058, Erlangen, Germany
| | - Rainer A Böckmann
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Staudtstrasse 5, 91058, Erlangen, Germany
| | - Petra Dietrich
- Molecular Plant Physiology, Department of Biology, University of Erlangen-Nürnberg, Staudtstrasse 5, 91058, Erlangen, Germany.
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116
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Abstract
The neurodegenerative movement disorder Parkinson disease (PD) is prevalent in the aged population. However, the underlying mechanisms that trigger disease are unclear. Increasing work implicates both impaired Ca2+ signalling and lysosomal dysfunction in neuronal demise. Here I aim to connect these distinct processes by exploring the evidence that lysosomal Ca2+ signalling is disrupted in PD. In particular, I highlight defects in lysosomal Ca2+ content and signalling through NAADP-regulated two-pore channels in patient fibroblasts harbouring mutations in the PD-linked genes, GBA1 and LRRK2. As an emerging contributor to PD pathogenesis, the lysosomal Ca2+ signalling apparatus could represent a novel therapeutic target.
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Affiliation(s)
- Bethan S Kilpatrick
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK
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117
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Feng X, Yang J. Lysosomal Calcium in Neurodegeneration. MESSENGER (LOS ANGELES, CALIF. : PRINT) 2016; 5:56-66. [PMID: 29082116 PMCID: PMC5659362 DOI: 10.1166/msr.2016.1055] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Lysosomes are the central organelles responsible for macromolecule recycling in the cell. Lysosomal dysfunction is the primary cause of lysosomal storage diseases (LSDs), and contributes significantly to the pathogenesis of common neurodegenerative diseases. The lysosomes are also intracellular stores for calcium ions, one of the most common second messenger in the cell. Lysosomal Ca2+ is required for diverse cellular processes including signal transduction, vesicular trafficking, autophagy, nutrient sensing, exocytosis, and membrane repair. In this review, we first summarize some recent progresses in the studies of lysosome Ca2+ regulation, with a focus on the newly discovered lysosomal Ca2+ channels and the mechanisms of lysosomal Ca2+ store refilling. We then discuss how defects in lysosomal Ca2+ release and store maintenance cause lysosomal dysfunction and neurodegeneration.
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Affiliation(s)
- Xinghua Feng
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
| | - Junsheng Yang
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
- The Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 3089 Natural Science Building (Kraus), 830 North University, Ann Arbor, MI 48109, USA
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118
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La Rovere RML, Roest G, Bultynck G, Parys JB. Intracellular Ca(2+) signaling and Ca(2+) microdomains in the control of cell survival, apoptosis and autophagy. Cell Calcium 2016; 60:74-87. [PMID: 27157108 DOI: 10.1016/j.ceca.2016.04.005] [Citation(s) in RCA: 201] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Revised: 04/14/2016] [Accepted: 04/15/2016] [Indexed: 01/01/2023]
Abstract
The endoplasmic reticulum (ER), mitochondria and lysosomes are physically and/or functionally linked, establishing close contact sites between these organelles. As a consequence, Ca(2+) release events from the ER, the major intracellular Ca(2+)-storage organelle, have an immediate effect on the physiological function of mitochondria and lysosomes. Also, the lysosomes can act as a Ca(2+) source for Ca(2+) release into the cytosol, thereby influencing ER-based Ca(2+) signaling. Given the important role for mitochondria and lysosomes in cell survival, cell death and cell adaptation processes, it has become increasingly clear that Ca(2+) signals from or towards these organelles impact these processes. In this review, we discuss the most recent insights in the emerging role of Ca(2+) signaling in cellular survival by controlling basal mitochondrial bioenergetics and by regulating apoptosis, a mitochondrial process, and autophagy, a lysosomal process, in response to cell damage and cell stress.
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Affiliation(s)
- Rita M L La Rovere
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, BE-3000 Leuven, Belgium
| | - Gemma Roest
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, BE-3000 Leuven, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, BE-3000 Leuven, Belgium.
| | - Jan B Parys
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, BE-3000 Leuven, Belgium.
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119
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Pitt SJ, Reilly-O'Donnell B, Sitsapesan R. Exploring the biophysical evidence that mammalian two-pore channels are NAADP-activated calcium-permeable channels. J Physiol 2016; 594:4171-9. [PMID: 26872338 DOI: 10.1113/jp270936] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/15/2016] [Indexed: 01/15/2023] Open
Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) potently releases Ca(2+) from acidic intracellular endolysosomal Ca(2+) stores. It is widely accepted that two types of two-pore channels, termed TPC1 and TPC2, are responsible for the NAADP-mediated Ca(2+) release but the underlying mechanisms regulating their gating appear to be different. For example, although both TPC1 and TPC2 are activated by NAADP, TPC1 appears to be additionally regulated by cytosolic Ca(2+) . Ion conduction and permeability also differ markedly. TPC1 and TPC2 are permeable to a range of cations although biophysical experiments suggest that TPC2 is slightly more selective for Ca(2+) over K(+) than TPC1 and hence capable of releasing greater quantities of Ca(2+) from acidic stores. TPC1 is also permeable to H(+) and therefore may play a role in regulating lysosomal and cytosolic pH, possibly creating localised acidic domains. The significantly different gating and ion conducting properties of TPC1 and TPC2 suggest that these two ion channels may play complementary physiological roles as Ca(2+) -release channels of the endolysosomal system.
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Affiliation(s)
- Samantha J Pitt
- School of Medicine, University of St Andrews, St Andrews, KY16 9TF, UK
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120
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Abstract
The Ca2+-mobilizing second messenger, NAADP (nicotinic acid adenine dinucleotide phosphate), has been with us for nearly 20 years and yet we still cannot fully agree on the identity of its target Ca2+-release channel. In spite of some recent robust challenges to the idea that two-pore channels (TPCs) represent the elusive "NAADP receptor", evidence continues to accumulate that TPCs are important for NAADP-mediated responses. This article will briefly outline the background and review more recent work pertaining to the TPC story.
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121
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Two-pore channels at the intersection of endolysosomal membrane traffic. Biochem Soc Trans 2016; 43:434-41. [PMID: 26009187 DOI: 10.1042/bst20140303] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Two-pore channels (TPCs) are ancient members of the voltage-gated ion channel superfamily that localize to acidic organelles such as lysosomes. The TPC complex is the proposed target of the Ca2+-mobilizing messenger NAADP, which releases Ca2+ from these acidic Ca2+ stores. Whereas details of TPC activation and native ion permeation remain unclear, a consensus has emerged around their function in regulating endolysosomal trafficking. This role is supported by recent proteomic data showing that TPCs interact with proteins controlling membrane organization and dynamics, including Rab GTPases and components of the fusion apparatus. Regulation of TPCs by PtdIns(3,5)P2 and/or NAADP (nicotinic acid adenine dinucleotide phosphate) together with their functional and physical association with Rab proteins provides a mechanism for coupling phosphoinositide and trafficking protein cues to local ion fluxes. Therefore, TPCs work at the regulatory cross-roads of (patho)physiological cues to co-ordinate and potentially deregulate traffic flow through the endolysosomal network. This review focuses on the native role of TPCs in trafficking and their emerging contributions to endolysosomal trafficking dysfunction.
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122
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Characterization of Two-Pore Channel 2 by Nuclear Membrane Electrophysiology. Sci Rep 2016; 6:20282. [PMID: 26838264 PMCID: PMC4738322 DOI: 10.1038/srep20282] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 12/30/2015] [Indexed: 02/07/2023] Open
Abstract
Lysosomal calcium (Ca2+) release mediated by NAADP triggers signalling cascades that regulate many cellular processes. The identification of two-pore channel 2 (TPC2) as the NAADP receptor advances our understanding of lysosomal Ca2+ signalling, yet the lysosome is not amenable to traditional patch-clamp electrophysiology. Previous attempts to record TPC2 single-channel activity put TPC2 outside its native environment, which not reflect TPC2’s true physiological properties. To test the feasibility of using nuclear membrane electrophysiology for TPC2 channel characterization, we constructed a stable human TPC2-expressing DT40TKO cell line that lacks endogenous InsP3R and RyR (DT40TKO-hTPC2). Immunostaining revealed hTPC2 expression on the ER and nuclear envelope. Intracellular dialysis of NAADP into Fura-2-loaded DT40TKO-hTPC2 cells elicited cytosolic Ca2+ transients, suggesting that hTPC2 was functionally active. Using nuclear membrane electrophysiology, we detected a ~220 pS single-channel current activated by NAADP with K+ as the permeant ion. The detected single-channel recordings displayed a linear current-voltage relationship, were sensitive to Ned-19 inhibition, were biphasically regulated by NAADP concentration, and regulated by PKA phosphorylation. In summary, we developed a cell model for the characterization of the TPC2 channel and the nuclear membrane patch-clamp technique provided an alternative approach to rigorously investigate the electrophysiological properties of TPC2 with minimal manipulation.
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123
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Guse AH, Wolf IMA. Ca(2+) microdomains, NAADP and type 1 ryanodine receptor in cell activation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1379-84. [PMID: 26804481 DOI: 10.1016/j.bbamcr.2016.01.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 01/05/2016] [Accepted: 01/18/2016] [Indexed: 02/04/2023]
Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a Ca(2+) mobilizing second messenger that belongs to the superfamily of regulatory adenine nucleotides. Though NAADP has been known since 20 years, several aspects of its metabolism and molecular mode of action are still under discussion. Though the importance of the type 1 ryanodine receptor was discovered and published already in 2002 Hohenegger et al. (2002 Oct 15), recent data re-emphasize these original findings in pancreatic acinar cells and in T-lymphocytes. Here we review recent developments in NAADP formation and metabolism, putative target Ca(2+) channels for NAADP with special emphasis on the type 1 ryanodine receptor, and NAADP binding proteins. The latter are basis for a unifying hypothesis for NAADP action. Finally, the role of NAADP in T cell Ca(2+) signaling and activation is discussed. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen.
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Affiliation(s)
- Andreas H Guse
- The Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
| | - Insa M A Wolf
- The Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
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124
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Cane MC, Parrington J, Rorsman P, Galione A, Rutter GA. The two pore channel TPC2 is dispensable in pancreatic β-cells for normal Ca²⁺ dynamics and insulin secretion. Cell Calcium 2015; 59:32-40. [PMID: 26769314 PMCID: PMC4751975 DOI: 10.1016/j.ceca.2015.12.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/08/2015] [Accepted: 12/21/2015] [Indexed: 12/21/2022]
Abstract
Ca(2+) signals are central to the stimulation of insulin secretion from pancreatic β-cells by glucose and other agents, including glucagon-like peptide-1 (GLP-1). Whilst Ca(2+) influx through voltage-gated Ca(2+) channels on the plasma membrane is a key trigger for glucose-stimulated secretion, mobilisation of Ca(2+) from acidic stores has been implicated in the control of more localised Ca(2+) changes and membrane potential. Nicotinic acid adenine dinucleotide phosphate (NAADP), generated in β-cells in response to high glucose, is a potent mobiliser of these stores, and has been proposed to act through two pore channels (TPC1 and TPC2, murine gene names Tpcn1 and Tpcn2). Whilst the role of TPC1 in the control of Ca(2+) mobilisation and insulin secretion was recently confirmed, conflicting data exist for TPC2. Here, we used the selective and efficient deleter strain, Ins1Cre to achieve β-cell selective deletion of the Tpcn2 gene in mice. βTpcn2 KO mice displayed normal intraperitoneal and oral glucose tolerance, and glucose-stimulated Ca(2+) dynamics and insulin secretion from islets were similarly normal. GLP-1-induced Ca(2+) increases involved an increase in oscillation frequency from 4.35 to 4.84 per minute (p=0.04) at 8mM glucose, and this increase was unaffected by the absence of Tpcn2. The current data thus indicate that TPC2 is not absolutely required for normal glucose- or incretin-stimulated insulin secretion from the β-cell. Our findings suggest that TPC1, whose expression tended to increase in Tpcn2 null islets, might be sufficient to support normal Ca(2+) dynamics in response to stimulation by nutrients or incretins.
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Affiliation(s)
- Matthew C Cane
- Section of Cell Biology and Functional Genomics, Imperial College London, Du Cane Road, W12 0NN London, UK
| | - John Parrington
- Department of Pharmacology, University of Oxford, Mansfield Road, OX1 3QT, UK
| | - Patrik Rorsman
- The Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, OX1 3QT, UK
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Imperial College London, Du Cane Road, W12 0NN London, UK.
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125
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Structure of the voltage-gated two-pore channel TPC1 from Arabidopsis thaliana. Nature 2015; 531:196-201. [PMID: 26689363 PMCID: PMC4841471 DOI: 10.1038/nature16446] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 11/10/2015] [Indexed: 12/11/2022]
Abstract
Two-pore channels (TPCs) contain two copies of a Shaker-like six-transmembrane (6-TM) domain in each subunit and are ubiquitously expressed in both animals and plants as organellar cation channels. Here, we present the first crystal structure of a vacuolar two-pore channel from Arabidopsis thaliana, AtTPC1, which functions as a homodimer. AtTPC1 activation requires both voltage and cytosolic Ca2+. Ca2+ binding to the cytosolic EF-hand domain triggers conformational changes coupled to the pair of pore-lining inner helices (IS6 helices) from the first 6-TM domains, whereas membrane potential only activates the second voltage-sensing domain (VSD2) whose conformational changes are coupled to the pair of inner helices (IIS6 helices) from the second 6-TM domains. Luminal Ca2+ or Ba2+ can modulate voltage activation by stabilizing VSD2 in the resting state and shifts voltage activation towards more positive potentials. Our Ba2+ bound AtTPC1 structure reveals a voltage sensor in the resting state, providing hitherto unseen structural insight into the general voltage-gating mechanism among voltage-gated channels.
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126
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Horton JS, Wakano CT, Speck M, Stokes AJ. Two-pore channel 1 interacts with citron kinase, regulating completion of cytokinesis. Channels (Austin) 2015; 9:21-9. [PMID: 25665131 PMCID: PMC4594595 DOI: 10.4161/19336950.2014.978676] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Two-pore channels (TPC1, 2, and 3) are recently identified endolysosmal ion channels, but remain poorly characterized. In this study, we show for the first time a role for TPC1 in cytokinesis, the final step in cell division. HEK 293 T-REx cells inducibly overexpressing TPC1 demonstrated a lack of proliferation accompanied by multinucleation and an increase in G2/M cycling cells. Increased TPC1 was associated with a concomitant accumulation of active RhoGTP and a decrease in phosphorylated myosin light chain (MLC). Finally, we demonstrated a novel interaction between TPC1 and citron kinase (CIT). These results identify TPC1 as a central component of cytokinetic control, specifically during abscission, and introduce a means by which the endolysosomal system may play an active role in this process.
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Affiliation(s)
- Jaime S Horton
- a Laboratory of Experimental Medicine; John A. Burns School of Medicine ; University of Hawaii ; Honolulu , HI USA
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127
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Capel RA, Bolton EL, Lin WK, Aston D, Wang Y, Liu W, Wang X, Burton RAB, Bloor-Young D, Shade KT, Ruas M, Parrington J, Churchill GC, Lei M, Galione A, Terrar DA. Two-pore Channels (TPC2s) and Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) at Lysosomal-Sarcoplasmic Reticular Junctions Contribute to Acute and Chronic β-Adrenoceptor Signaling in the Heart. J Biol Chem 2015; 290:30087-98. [PMID: 26438825 PMCID: PMC4705968 DOI: 10.1074/jbc.m115.684076] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Indexed: 12/12/2022] Open
Abstract
Ca2+-permeable type 2 two-pore channels (TPC2) are lysosomal proteins required for nicotinic acid adenine dinucleotide phosphate (NAADP)-evoked Ca2+ release in many diverse cell types. Here, we investigate the importance of TPC2 proteins for the physiology and pathophysiology of the heart. NAADP-AM failed to enhance Ca2+ responses in cardiac myocytes from Tpcn2−/− mice, unlike myocytes from wild-type (WT) mice. Ca2+/calmodulin-dependent protein kinase II inhibitors suppressed actions of NAADP in myocytes. Ca2+ transients and contractions accompanying action potentials were increased by isoproterenol in myocytes from WT mice, but these effects of β-adrenoreceptor stimulation were reduced in myocytes from Tpcn2−/− mice. Increases in amplitude of L-type Ca2+ currents evoked by isoproterenol remained unchanged in myocytes from Tpcn2−/− mice showing no loss of β-adrenoceptors or coupling mechanisms. Whole hearts from Tpcn2−/− mice also showed reduced inotropic effects of isoproterenol and a reduced tendency for arrhythmias following acute β-adrenoreceptor stimulation. Hearts from Tpcn2−/− mice chronically exposed to isoproterenol showed less cardiac hypertrophy and increased threshold for arrhythmogenesis compared with WT controls. Electron microscopy showed that lysosomes form close contacts with the sarcoplasmic reticulum (separation ∼25 nm). We propose that Ca2+-signaling nanodomains between lysosomes and sarcoplasmic reticulum dependent on NAADP and TPC2 comprise an important element in β-adrenoreceptor signal transduction in cardiac myocytes. In summary, our observations define a role for NAADP and TPC2 at lysosomal/sarcoplasmic reticulum junctions as unexpected but major contributors in the acute actions of β-adrenergic signaling in the heart and also in stress pathways linking chronic stimulation of β-adrenoceptors to hypertrophy and associated arrhythmias.
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Affiliation(s)
- Rebecca A Capel
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Emma L Bolton
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Wee K Lin
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Daniel Aston
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Yanwen Wang
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Wei Liu
- the Faculty of Life Science, University of Manchester, Manchester M13 9NT, and
| | - Xin Wang
- the Faculty of Life Science, University of Manchester, Manchester M13 9NT, and
| | - Rebecca-Ann B Burton
- the Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Sherrington Road, Oxford OX1 3PT, United Kingdom
| | - Duncan Bloor-Young
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Kai-Ting Shade
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Margarida Ruas
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - John Parrington
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Grant C Churchill
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Ming Lei
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Antony Galione
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT
| | - Derek A Terrar
- From the Department of Pharmacology, BHF Centre of Research Excellence, University of Oxford, Mansfield Road, Oxford OX1 3QT,
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128
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Arredouani A, Ruas M, Collins SC, Parkesh R, Clough F, Pillinger T, Coltart G, Rietdorf K, Royle A, Johnson P, Braun M, Zhang Q, Sones W, Shimomura K, Morgan AJ, Lewis AM, Chuang KT, Tunn R, Gadea J, Teboul L, Heister PM, Tynan PW, Bellomo EA, Rutter GA, Rorsman P, Churchill GC, Parrington J, Galione A. Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) and Endolysosomal Two-pore Channels Modulate Membrane Excitability and Stimulus-Secretion Coupling in Mouse Pancreatic β Cells. J Biol Chem 2015; 290:21376-92. [PMID: 26152717 PMCID: PMC4571866 DOI: 10.1074/jbc.m115.671248] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Indexed: 12/02/2022] Open
Abstract
Pancreatic β cells are electrically excitable and respond to elevated glucose concentrations with bursts of Ca2+ action potentials due to the activation of voltage-dependent Ca2+ channels (VDCCs), which leads to the exocytosis of insulin granules. We have examined the possible role of nicotinic acid adenine dinucleotide phosphate (NAADP)-mediated Ca2+ release from intracellular stores during stimulus-secretion coupling in primary mouse pancreatic β cells. NAADP-regulated Ca2+ release channels, likely two-pore channels (TPCs), have recently been shown to be a major mechanism for mobilizing Ca2+ from the endolysosomal system, resulting in localized Ca2+ signals. We show here that NAADP-mediated Ca2+ release from endolysosomal Ca2+ stores activates inward membrane currents and depolarizes the β cell to the threshold for VDCC activation and thereby contributes to glucose-evoked depolarization of the membrane potential during stimulus-response coupling. Selective pharmacological inhibition of NAADP-evoked Ca2+ release or genetic ablation of endolysosomal TPC1 or TPC2 channels attenuates glucose- and sulfonylurea-induced membrane currents, depolarization, cytoplasmic Ca2+ signals, and insulin secretion. Our findings implicate NAADP-evoked Ca2+ release from acidic Ca2+ storage organelles in stimulus-secretion coupling in β cells.
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Affiliation(s)
- Abdelilah Arredouani
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom,
| | - Margarida Ruas
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Stephan C Collins
- the Centre des Sciences du Gout et de l'Alimentation, Equipe 5, 9E Boulevard Jeanne d'Arc 21000 Dijon, France
| | - Raman Parkesh
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Frederick Clough
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Toby Pillinger
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - George Coltart
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Katja Rietdorf
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Andrew Royle
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Paul Johnson
- the Nuffield Department of Surgery, John Radcliffe Hospital, Headley Way, Headington, Oxford OX3 9DU, United Kingdom
| | - Matthias Braun
- the The Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford OX3 7LJ, United Kingdom
| | - Quan Zhang
- the The Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford OX3 7LJ, United Kingdom
| | - William Sones
- the The Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford OX3 7LJ, United Kingdom
| | - Kenju Shimomura
- the Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy, and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, United Kingdom
| | - Anthony J Morgan
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Alexander M Lewis
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Kai-Ting Chuang
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Ruth Tunn
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Joaquin Gadea
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Lydia Teboul
- The Mary Lyon Centre, Medical Research Council Harwell, Oxfordshire OX11 0RD, United Kingdom
| | - Paula M Heister
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Patricia W Tynan
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Elisa A Bellomo
- the Centre des Sciences du Gout et de l'Alimentation, Equipe 5, 9E Boulevard Jeanne d'Arc 21000 Dijon, France
| | - Guy A Rutter
- the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Medicine, Imperial College London, Hammersmith Hospital, du Cane Road, London W12 0NN, United Kingdom, and
| | - Patrik Rorsman
- the The Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford OX3 7LJ, United Kingdom
| | - Grant C Churchill
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - John Parrington
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom,
| | - Antony Galione
- From the Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom,
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129
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Abstract
Two-pore channels (TPCs) are evolutionarily important members of the voltage-gated ion channel superfamily. TPCs localize to acidic Ca(2+) stores within the endolysosomal system. Most evidence indicate that TPCs mediate Ca(2+) signals through the Ca(2+)-mobilizing messenger nicotinic acid adenine dinucleotide phosphate (NAADP) to control a range of Ca(2+)-dependent events. Recent studies clarify the mechanism of TPC activation and identify roles for TPCs in disease, highlighting the regulation of endolysosomal membrane traffic by local Ca(2+) fluxes. Chemical targeting of TPCs to maintain endolysosomal "well-being" may be beneficial in disorders as diverse as Parkinson's disease, fatty liver disease, and Ebola virus infection.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK. E-mail:
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130
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Abstract
More potent, but less known than IP3 that liberates Ca2+ from the ER, NAADP releases Ca2+ from acidic stores. The notion that TPC channels mediate this Ca2+ release was questioned recently by studies suggesting that TPCs are rather PI(3,5)P2-activated Na+ channels. Ruas et al (2015) now partially reconcile these views by showing that TPCs significantly conduct both cations and confirm their activation by both NAADP and PI(3,5)P2. They attribute the failure of others to observe TPC-dependent NAADP-induced Ca2+ release in vivo to inadequate mouse models that retain partial TPC function.
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Affiliation(s)
- Thomas J Jentsch
- Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP)Berlin, Germany
- Max-Delbrück-Centrum für Molekulare Medizin (MDC) in der Helmholtz GemeinschaftBerlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin BerlinBerlin, Germany
| | - Maja B Hoegg-Beiler
- Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP)Berlin, Germany
- Max-Delbrück-Centrum für Molekulare Medizin (MDC) in der Helmholtz GemeinschaftBerlin, Germany
| | - Janis Vogt
- Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP)Berlin, Germany
- Max-Delbrück-Centrum für Molekulare Medizin (MDC) in der Helmholtz GemeinschaftBerlin, Germany
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132
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Ruas M, Galione A, Parrington J. Two-Pore Channels: Lessons from Mutant Mouse Models. ACTA ACUST UNITED AC 2015; 4:4-22. [PMID: 27330869 DOI: 10.1166/msr.2015.1041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent interest in two-pore channels (TPCs) has resulted in a variety of studies dealing with the functional role and mechanism of action of these endo-lysosomal proteins in diverse physiological processes. With the availability of mouse lines harbouring mutant alleles for Tpcnl and/or Tpcn2 genes, several studies have made use of them to validate, consolidate and discover new roles for these channels not only at the cellular level but, importantly, also at the level of the whole organism. The different mutant mouse lines that have been used were derived from distinct genetic manipulation strategies, with the aim of knocking out expression of TPC proteins. However, the expression of different residual TPC sequences predicted to occur in these mutant mouse lines, together with the varied degree to which the effects on Tpcn expression have been studied, makes it important to assess the true knockout status of some of the lines. In this review we summarize these Tpcn mutant mouse lines with regard to their predicted effect on Tpcn expression and the extent to which they have been characterized. Additionally, we discuss how results derived from studies using these Tpcn mutant mouse lines have consolidated previously proposed roles for TPCs, such as mediators of NAADP signalling, endo-lysosomal functions, and pancreatic β cell physiology. We will also review how they have been instrumental in the assignment of new physiological roles for these cation channels in processes such as membrane electrical excitability, neoangiogenesis, viral infection and brown adipose tissue and heart function, revealing, in some cases, a specific contribution of a particular TPC isoform.
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Affiliation(s)
- Margarida Ruas
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - John Parrington
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
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133
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Abstract
Two-pore channels are members of the voltage-gated ion channel superfamily. They localise to the endolysosomal system and are likely targets for the Ca2+ mobilising messenger NAADP. In this brief review, we relate mutagenesis of the TPC pore to a recently published homology model and discuss how pore mutants are informing us of TPC function. Molecular physiology of these ubiquitous proteins is thus emerging.
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Affiliation(s)
- Christopher J Penny
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT
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134
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Ruas M, Davis LC, Chen CC, Morgan AJ, Chuang KT, Walseth TF, Grimm C, Garnham C, Powell T, Platt N, Platt FM, Biel M, Wahl-Schott C, Parrington J, Galione A. Expression of Ca²⁺-permeable two-pore channels rescues NAADP signalling in TPC-deficient cells. EMBO J 2015; 34:1743-58. [PMID: 25872774 PMCID: PMC4516428 DOI: 10.15252/embj.201490009] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 03/11/2015] [Indexed: 01/26/2023] Open
Abstract
The second messenger NAADP triggers Ca2+ release from endo-lysosomes. Although two-pore channels (TPCs) have been proposed to be regulated by NAADP, recent studies have challenged this. By generating the first mouse line with demonstrable absence of both Tpcn1 and Tpcn2 expression (Tpcn1/2−/−), we show that the loss of endogenous TPCs abolished NAADP-dependent Ca2+ responses as assessed by single-cell Ca2+ imaging or patch-clamp of single endo-lysosomes. In contrast, currents stimulated by PI(3,5)P2 were only partially dependent on TPCs. In Tpcn1/2−/− cells, NAADP sensitivity was restored by re-expressing wild-type TPCs, but not by mutant versions with impaired Ca2+-permeability, nor by TRPML1. Another mouse line formerly reported as TPC-null likely expresses truncated TPCs, but we now show that these truncated proteins still support NAADP-induced Ca2+ release. High-affinity [32P]NAADP binding still occurs in Tpcn1/2−/− tissue, suggesting that NAADP regulation is conferred by an accessory protein. Altogether, our data establish TPCs as Ca2+-permeable channels indispensable for NAADP signalling.
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Affiliation(s)
- Margarida Ruas
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Lianne C Davis
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Cheng-Chang Chen
- Center for Integrated Protein Science CIPS-M and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | | | - Kai-Ting Chuang
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Timothy F Walseth
- Pharmacology Department, University of Minnesota, Minneapolis, MN, USA
| | - Christian Grimm
- Center for Integrated Protein Science CIPS-M and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | - Clive Garnham
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Trevor Powell
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Nick Platt
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Frances M Platt
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Martin Biel
- Center for Integrated Protein Science CIPS-M and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | - Christian Wahl-Schott
- Center for Integrated Protein Science CIPS-M and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | - John Parrington
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Oxford, UK
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135
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Penny CJ, Kilpatrick BS, Eden ER, Patel S. Coupling acidic organelles with the ER through Ca²⁺ microdomains at membrane contact sites. Cell Calcium 2015; 58:387-96. [PMID: 25866010 DOI: 10.1016/j.ceca.2015.03.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 03/13/2015] [Accepted: 03/14/2015] [Indexed: 10/23/2022]
Abstract
Acidic organelles such as lysosomes serve as non-canonical Ca(2+) stores. The Ca(2+) mobilising messenger NAADP is thought to trigger local Ca(2+) release from such stores. These events are then amplified by Ca(2+) channels on canonical ER Ca(2+) stores to generate physiologically relevant global Ca(2+) signals. Coupling likely occurs at microdomains formed at membrane contact sites between acidic organelles and the ER. Molecular analyses and computational modelling suggest heterogeneity in the composition of these contacts and predicted Ca(2+) microdomain behaviour. Conversely, acidic organelles might also locally amplify and temper ER-evoked Ca(2+) signals. Ca(2+) microdomains between distinct Ca(2+) stores are thus likely to be integral to the genesis of complex Ca(2+) signals.
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Affiliation(s)
- Christopher J Penny
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Bethan S Kilpatrick
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Emily R Eden
- Department of Cell Biology, Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK.
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136
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Lear PV, González-Touceda D, Porteiro Couto B, Viaño P, Guymer V, Remzova E, Tunn R, Chalasani A, García-Caballero T, Hargreaves IP, Tynan PW, Christian HC, Nogueiras R, Parrington J, Diéguez C. Absence of intracellular ion channels TPC1 and TPC2 leads to mature-onset obesity in male mice, due to impaired lipid availability for thermogenesis in brown adipose tissue. Endocrinology 2015; 156:975-86. [PMID: 25545384 PMCID: PMC4330317 DOI: 10.1210/en.2014-1766] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 12/23/2014] [Indexed: 12/11/2022]
Abstract
Intracellular calcium-permeable channels have been implicated in thermogenic function of murine brown and brite/beige adipocytes, respectively transient receptor potential melastin-8 and transient receptor potential vanilloid-4. Because the endo-lysosomal two-pore channels (TPCs) have also been ascribed with metabolic functionality, we studied the effect of simultaneously knocking out TPC1 and TPC2 on body composition and energy balance in male mice fed a chow diet. Compared with wild-type mice, TPC1 and TPC2 double knockout (Tpcn1/2(-/-)) animals had a higher respiratory quotient and became obese between 6 and 9 months of age. Although food intake was unaltered, interscapular brown adipose tissue (BAT) maximal temperature and lean-mass adjusted oxygen consumption were lower in Tpcn1/2(-/-) than in wild type mice. Phosphorylated hormone-sensitive lipase expression, lipid density and expression of β-adrenergic receptors were also lower in Tpcn1/2(-/-) BAT, whereas mitochondrial respiratory chain function and uncoupling protein-1 expression remained intact. We conclude that Tpcn1/2(-/-) mice show mature-onset obesity due to reduced lipid availability and use, and a defect in β-adrenergic receptor signaling, leading to impaired thermogenic activity, in BAT.
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Affiliation(s)
- Pamela V. Lear
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | | | | | - Patricia Viaño
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | - Vanessa Guymer
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | - Elena Remzova
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | - Ruth Tunn
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | - Annapurna Chalasani
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | - Tomás García-Caballero
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | - Iain P. Hargreaves
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | - Patricia W. Tynan
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | - Helen C. Christian
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
| | - Rubén Nogueiras
- Department of Physiology (P.V.L., D.G.-T., B.P.C., R.N., C.D.), Centre for Research in Molecular Medicine and Chronic Diseases, University of Santiago de Compostela and Institute of Health Sciences, and Department of Morphological Sciences (P.V., T.G.-C.), School of Medicine and University Clinical Hospital, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Pharmacology (P.V.L., R.T., P.W.T., J.P.), Oxford University, Oxford OX1 3QT, United Kingdom; Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (D.G.-T., B.P.C., R.N., C.D.), 15706, Santiago de Compostela, Spain; Department of Physiology, Anatomy, and Genetics (V.G., H.C.C.), Oxford University, Oxford OX1 3QX, United Kingdom; and Neurometabolic Unit (E.R., A.C., I.P.H.), National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, United Kingdom
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137
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Ezeani M, Omabe M. A New Perspective of Lysosomal Cation Channel-Dependent Homeostasis in Alzheimer's Disease. Mol Neurobiol 2015; 53:1672-1678. [PMID: 25691454 DOI: 10.1007/s12035-015-9108-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 01/20/2015] [Indexed: 01/08/2023]
Abstract
Studies have reported typically biophysical lysosomal cation channels including TPCs. Their plausible biological roles are being elucidated by pharmacological, genetic and conventional patch clamp procedures. The best characterized so far among these channels is the ML1 isoform of TRP. The reported TRPs and TPCs are bypass for cation fluxes and are strategic for homeostasis of ionic milieu of the acidic organelles they confine to. Ca(2+) homeostasis and adequate acidic pHL are critically influential for the regulation of a plethora of biological functions these intracellular cation channels perform. In lysosomal ion channel biology, we review: ML1 and TPC2 in Ca(2+) signaling, ML1 and TPC2 in pH(L) regulation. Using Aβ42 and tau proteins found along clathrin endolysosomal internalization pathway (Fig. 3), we proffer a mechanism of abnormal pH(L) and ML1/TPC2-dependent cation homeostasis in AD.
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Affiliation(s)
- Martin Ezeani
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, B3H 4R2, Nova Scotia, Canada.
| | - Maxwell Omabe
- Cancer Research Unit, Saskatchewan Cancer Agency, Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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138
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Morgan AJ, Davis LC, Galione A. Imaging approaches to measuring lysosomal calcium. Methods Cell Biol 2015; 126:159-95. [DOI: 10.1016/bs.mcb.2014.10.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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139
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Abstract
Ebola virus is an enveloped virus with filamentous structure and causes a severe hemorrhagic fever in human and nonhuman primates. Host cell entry is the first essential step in the viral life cycle, which has been extensively studied as one of the therapeutic targets. A virus factor of cell entry is a surface glycoprotein (GP), which is an only essential viral protein in the step, as well as the unique particle structure. The virus also interacts with a lot of host factors to successfully enter host cells. Ebola virus at first binds to cell surface proteins and internalizes into cells, followed by trafficking through endosomal vesicles to intracellular acidic compartments. There, host proteases process GPs, which can interact with an intracellular receptor. Then, under an appropriate circumstance, viral and endosomal membranes are fused, which is enhanced by major structural changes of GPs, to complete host cell entry. Recently the basic research of Ebola virus infection mechanism has markedly progressed, largely contributed by identification of host factors and detailed structural analyses of GPs. This article highlights the mechanism of Ebola virus host cell entry, including recent findings.
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140
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Ogunbayo OA, Zhu Y, Shen B, Agbani E, Li J, Ma J, Zhu MX, Evans AM. Organelle-specific subunit interactions of the vertebrate two-pore channel family. J Biol Chem 2014; 290:1086-95. [PMID: 25451935 DOI: 10.1074/jbc.m114.610493] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The organellar targeting of two-pore channels (TPCs) and their capacity to associate as homo- and heterodimers may be critical to endolysosomal signaling. A more detailed understanding of the functional association of vertebrate TPC1-3 is therefore necessary. We report here that when stably expressed in HEK293 cells, human (h) TPC1 and chicken (c) TPC3 were specifically targeted to different subpopulations of endosomes, hTPC2 was specifically targeted to lysosomes, and rabbit (r) TPC3 was specifically targeted to both endosomes and lysosomes. Intracellular dialysis of NAADP evoked a Ca(2+) transient in HEK293 cells that stably overexpressed hTPC1, hTPC2, and rTPC3, but not in cells that stably expressed cTPC3. The Ca(2+) transients induced in cells that overexpressed endosome-targeted hTPC1 were abolished upon depletion of acidic Ca(2+) stores by bafilomycin A1, but remained unaffected following depletion of endoplasmic reticulum stores by thapsigargin. In contrast, Ca(2+) transients induced via lysosome-targeted hTPC2 and endolysosome-targeted rTPC3 were abolished by bafilomycin A1 and markedly attenuated by thapsigargin. NAADP induced marked Ca(2+) transients in HEK293 cells that stably coexpressed hTPC2 with hTPC1 or cTPC3, but failed to evoke any such response in cells that coexpressed interacting hTPC2 and rTPC3 subunits. We therefore conclude that 1) all three TPC subtypes may support Ca(2+) signaling from their designate acidic stores, and 2) lysosome-targeted (but not endosome-targeted) TPCs support coupling to the endoplasmic reticulum.
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Affiliation(s)
- Oluseye A Ogunbayo
- From the Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh EH8 9XD, Scotland, United Kingdom
| | - Yingmin Zhu
- the Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Bing Shen
- the Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas 77030, the Department of Physiology, Anhui Medical University, Hefei, Anhui 230032, China, and
| | - Ejaife Agbani
- From the Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh EH8 9XD, Scotland, United Kingdom
| | - Jie Li
- the Department of Physiology, Anhui Medical University, Hefei, Anhui 230032, China, and
| | - Jianjie Ma
- the Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio 43210
| | - Michael X Zhu
- the Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas 77030,
| | - A Mark Evans
- From the Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh EH8 9XD, Scotland, United Kingdom,
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141
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Hockey LN, Kilpatrick BS, Eden ER, Lin-Moshier Y, Brailoiu GC, Brailoiu E, Futter CE, Schapira AH, Marchant JS, Patel S. Dysregulation of lysosomal morphology by pathogenic LRRK2 is corrected by TPC2 inhibition. J Cell Sci 2014; 128:232-8. [PMID: 25416817 PMCID: PMC4294771 DOI: 10.1242/jcs.164152] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Two-pore channels (TPCs) are endolysosomal ion channels implicated in Ca2+ signalling from acidic organelles. The relevance of these ubiquitous proteins for human disease, however, is unclear. Here, we report that lysosomes are enlarged and aggregated in fibroblasts from Parkinson disease patients with the common G2019S mutation in LRRK2. Defects were corrected by molecular silencing of TPC2, pharmacological inhibition of TPC regulators [Rab7, NAADP and PtdIns(3,5)P2] and buffering local Ca2+ increases. NAADP-evoked Ca2+ signals were exaggerated in diseased cells. TPC2 is thus a potential drug target within a pathogenic LRRK2 cascade that disrupts Ca2+-dependent trafficking in Parkinson disease.
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Affiliation(s)
- Leanne N Hockey
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Bethan S Kilpatrick
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Emily R Eden
- Department of Cell Biology, Institute of Ophthalmology, University College London, London, EC1V 9EL, UK
| | - Yaping Lin-Moshier
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota, 55455, USA
| | - G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Thomas Jefferson University, Jefferson School of Pharmacy, Philadelphia, 19107, USA
| | - Eugen Brailoiu
- Department of Pharmacology and Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, 19140, USA
| | - Clare E Futter
- Department of Cell Biology, Institute of Ophthalmology, University College London, London, EC1V 9EL, UK
| | - Anthony H Schapira
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London, NW3 2PF, UK
| | - Jonathan S Marchant
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota, 55455, USA
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
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142
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Ramos I, Reich A, Wessel GM. Two-pore channels function in calcium regulation in sea star oocytes and embryos. Development 2014; 141:4598-609. [PMID: 25377554 DOI: 10.1242/dev.113563] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Egg activation at fertilization is an excellent process for studying calcium regulation. Nicotinic acid adenine dinucleotide-phosphate (NAADP), a potent calcium messenger, is able to trigger calcium release, likely through two-pore channels (TPCs). Concomitantly, a family of ectocellular enzymes, the ADP-ribosyl cyclases (ARCs), has emerged as being able to change their enzymatic mode from one of nucleotide cyclization in formation of cADPR to a base-exchange reaction in the generation of NAADP. Using sea star oocytes we gain insights into the functions of endogenously expressed TPCs and ARCs in the context of the global calcium signals at fertilization. Three TPCs and one ARC were found in the sea star (Patiria miniata) that were localized in the cortex of the oocytes and eggs. PmTPCs were localized in specialized secretory organelles called cortical granules, and PmARCs accumulated in a different, unknown, set of vesicles, closely apposed to the cortical granules in the egg cortex. Using morpholino knockdown of PmTPCs and PmARC in the oocytes, we found that both calcium regulators are essential for early embryo development, and that knockdown of PmTPCs leads to aberrant construction of the fertilization envelope at fertilization and changes in cortical granule pH. The calcium signals at fertilization are not significantly altered when individual PmTPCs are silenced, but the timing and shape of the cortical flash and calcium wave are slightly changed when the expression of all three PmTPCs is perturbed concomitantly, suggesting a cooperative activity among TPC isoforms in eliciting calcium signals that may influence localized physiological activities.
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Affiliation(s)
- Isabela Ramos
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI 02912, USA Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941, Brazil
| | - Adrian Reich
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Gary M Wessel
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI 02912, USA
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143
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Favia A, Desideri M, Gambara G, D'Alessio A, Ruas M, Esposito B, Del Bufalo D, Parrington J, Ziparo E, Palombi F, Galione A, Filippini A. VEGF-induced neoangiogenesis is mediated by NAADP and two-pore channel-2-dependent Ca2+ signaling. Proc Natl Acad Sci U S A 2014; 111:E4706-15. [PMID: 25331892 PMCID: PMC4226099 DOI: 10.1073/pnas.1406029111] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Vascular endothelial growth factor (VEGF) and its receptors VEGFR1/VEGFR2 play major roles in controlling angiogenesis, including vascularization of solid tumors. Here we describe a specific Ca(2+) signaling pathway linked to the VEGFR2 receptor subtype, controlling the critical angiogenic responses of endothelial cells (ECs) to VEGF. Key steps of this pathway are the involvement of the potent Ca(2+) mobilizing messenger, nicotinic acid adenine-dinucleotide phosphate (NAADP), and the specific engagement of the two-pore channel TPC2 subtype on acidic intracellular Ca(2+) stores, resulting in Ca(2+) release and angiogenic responses. Targeting this intracellular pathway pharmacologically using the NAADP antagonist Ned-19 or genetically using Tpcn2(-/-) mice was found to inhibit angiogenic responses to VEGF in vitro and in vivo. In human umbilical vein endothelial cells (HUVECs) Ned-19 abolished VEGF-induced Ca(2+) release, impairing phosphorylation of ERK1/2, Akt, eNOS, JNK, cell proliferation, cell migration, and capillary-like tube formation. Interestingly, Tpcn2 shRNA treatment abolished VEGF-induced Ca(2+) release and capillary-like tube formation. Importantly, in vivo VEGF-induced vessel formation in matrigel plugs in mice was abolished by Ned-19 and, most notably, failed to occur in Tpcn2(-/-) mice, but was unaffected in Tpcn1(-/-) animals. These results demonstrate that a VEGFR2/NAADP/TPC2/Ca(2+) signaling pathway is critical for VEGF-induced angiogenesis in vitro and in vivo. Given that VEGF can elicit both pro- and antiangiogenic responses depending upon the balance of signal transduction pathways activated, targeting specific VEGFR2 downstream signaling pathways could modify this balance, potentially leading to more finely tailored therapeutic strategies.
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Affiliation(s)
- Annarita Favia
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy
| | - Marianna Desideri
- Experimental Chemotherapy Laboratory, Regina Elena National Cancer Institute, 00128 Rome, Italy
| | - Guido Gambara
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy
| | - Alessio D'Alessio
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy; Institute of Histology and Embryology, Catholic University of the Sacred Heart, 00168 Rome, Italy; and
| | - Margarida Ruas
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom
| | - Bianca Esposito
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy
| | - Donatella Del Bufalo
- Experimental Chemotherapy Laboratory, Regina Elena National Cancer Institute, 00128 Rome, Italy
| | - John Parrington
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom
| | - Elio Ziparo
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy
| | - Fioretta Palombi
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom
| | - Antonio Filippini
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy;
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144
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Galione A. A primer of NAADP-mediated Ca(2+) signalling: From sea urchin eggs to mammalian cells. Cell Calcium 2014; 58:27-47. [PMID: 25449298 DOI: 10.1016/j.ceca.2014.09.010] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 09/28/2014] [Accepted: 09/29/2014] [Indexed: 02/04/2023]
Abstract
Since the discovery of the Ca(2+) mobilizing effects of the pyridine nucleotide metabolite, nicotinic acid adenine dinucleotide phosphate (NAADP), this molecule has been demonstrated to function as a Ca(2+) mobilizing intracellular messenger in a wide range of cell types. In this review, I will briefly summarize the distinct principles behind NAADP-mediated Ca(2+) signalling before going on to outline the role of this messenger in the physiology of specific cell types. Central to the discussion here is the finding that NAADP principally mobilizes Ca(2+) from acidic organelles such as lysosomes and it is this property that allows NAADP to play a unique role in intracellular Ca(2+) signalling. Lysosomes and related organelles are small Ca(2+) stores but importantly may also initiate a two-way dialogue with other Ca(2+) storage organelles to amplify Ca(2+) release, and may be strategically localized to influence localized Ca(2+) signalling microdomains. The study of NAADP signalling has created a new and fruitful focus on the lysosome and endolysosomal system as major players in calcium signalling and pathophysiology.
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Affiliation(s)
- Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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145
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Grimm C, Holdt LM, Chen CC, Hassan S, Müller C, Jörs S, Cuny H, Kissing S, Schröder B, Butz E, Northoff B, Castonguay J, Luber CA, Moser M, Spahn S, Lüllmann-Rauch R, Fendel C, Klugbauer N, Griesbeck O, Haas A, Mann M, Bracher F, Teupser D, Saftig P, Biel M, Wahl-Schott C. High susceptibility to fatty liver disease in two-pore channel 2-deficient mice. Nat Commun 2014; 5:4699. [DOI: 10.1038/ncomms5699] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 07/10/2014] [Indexed: 12/15/2022] Open
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146
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TPC1 has two variant isoforms, and their removal has different effects on endo-lysosomal functions compared to loss of TPC2. Mol Cell Biol 2014; 34:3981-92. [PMID: 25135478 PMCID: PMC4386455 DOI: 10.1128/mcb.00113-14] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Organelle ion homeostasis within the endo-lysosomal system is critical for physiological functions. Two-pore channels (TPCs) are cation channels that reside in endo-lysosomal organelles, and overexpression results in endo-lysosomal trafficking defects. However, the impact of a lack of TPC expression on endo-lysosomal trafficking is unknown. Here, we characterize Tpcn1 expression in two transgenic mouse lines (Tpcn1XG716 and Tpcn1T159) and show expression of a novel evolutionarily conserved Tpcn1B transcript from an alternative promoter, raising important questions regarding the status of Tpcn1 expression in mice recently described to be Tpcn1 knockouts. We show that the transgenic Tpcn1T159 line lacks expression of both Tpcn1 isoforms in all tissues analyzed. Using mouse embryonic fibroblasts (MEFs) from Tpcn1−/− and Tpcn2−/− animals, we show that a lack of Tpcn1 or Tpcn2 expression has no significant impact on resting endo-lysosomal pH or morphology. However, differential effects in endo-lysosomal function were observed upon the loss of Tpcn1 or Tpcn2 expression; thus, while Tpcn1−/− MEFs have impaired trafficking of cholera toxin from the plasma membrane to the Golgi apparatus, Tpcn2−/− MEFs show slower kinetics of ligand-induced platelet-derived growth factor receptor β (PDGFRβ) degradation, which is dependent on trafficking to lysosomes. Our findings indicate that TPC1 and TPC2 have important but distinct roles in the endo-lysosomal pathway.
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147
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Parrington J, Tunn R. Ca(2+) signals, NAADP and two-pore channels: role in cellular differentiation. Acta Physiol (Oxf) 2014; 211:285-96. [PMID: 24702694 DOI: 10.1111/apha.12298] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 02/13/2014] [Accepted: 03/27/2014] [Indexed: 02/06/2023]
Abstract
Ca(2+) signals regulate a wide range of physiological processes. Intracellular Ca(2+) stores can be mobilized in response to extracellular stimuli via a range of signal transduction mechanisms, often involving recruitment of diffusible second messenger molecules. The Ca(2+) -mobilizing messengers InsP3 and cADPR release Ca(2+) from the endoplasmic reticulum via the InsP3 and ryanodine receptors, respectively, while a third messenger, NAADP, releases Ca(2+) from acidic endosomes and lysosomes. Bidirectional communication between the endoplasmic reticulum (ER) and acidic organelles may have functional relevance for endolysosomal function as well as for the generation of Ca(2+) signals. The two-pore channels (TPCs) are currently strong candidates for being key components of NAADP-regulated Ca(2+) channels. Ca(2+) signals have been shown to play important roles in differentiation; however, much remains to be established about the exact signalling mechanisms involved. The investigation of the role of NAADP and TPCs in differentiation is still at an early stage, but recent studies have suggested that they are important mediators of differentiation of neurones, skeletal muscle cells and osteoclasts. NAADP signals and TPCs have also been implicated in autophagy, an important process in differentiation. Further studies will be required to identify the precise mechanism of TPC action and their link with NAADP signalling, as well as relating this to their roles in differentiation and other key processes in the cell and organism.
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Affiliation(s)
- J. Parrington
- Department of Pharmacology; University of Oxford; Oxford UK
| | - R. Tunn
- Department of Pharmacology; University of Oxford; Oxford UK
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148
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Pitt SJ, Lam AKM, Rietdorf K, Galione A, Sitsapesan R. Reconstituted human TPC1 is a proton-permeable ion channel and is activated by NAADP or Ca2+. Sci Signal 2014; 7:ra46. [PMID: 24847115 DOI: 10.1126/scisignal.2004854] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
NAADP potently triggers Ca2+ release from acidic lysosomal and endolysosomal Ca2+ stores. Human two-pore channels (TPC1 and TPC2), which are located on these stores, are involved in this process, but there is controversy over whether TPC1 and TPC2 constitute the Ca2+ release channels. We therefore examined the single-channel properties of human TPC1 after reconstitution into bilayers of controlled composition. We found that TPC1 was permeable not only to Ca2+ but also to monovalent cations and that permeability to protons was the highest (relative permeability sequence: H+ >> K+ > Na(+) ≥ Ca2+). NAADP or Ca2+ activated TPC1, and the presence of one of these ligands was required for channel activation. The endolysosome-located lipid phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] had no effect on TPC1 open probability but significantly increased the relative permeability of Na+ to Ca2+ and of H+ to Ca2+. Furthermore, our data showed that, although both TPC1 and TPC2 are stimulated by NAADP, these channels differ in ion selectivity and modulation by Ca2+ and pH. We propose that NAADP triggers H+ release from lysosomes and endolysomes through activation of TPC1, but that the Ca2+ -releasing ability of TPC1 will depend on the ionic composition of the acidic stores and may be influenced by other regulators that affect TPC1 ion permeation.
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Affiliation(s)
- Samantha J Pitt
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
| | - Andy K M Lam
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Katja Rietdorf
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Rebecca Sitsapesan
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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149
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Pereira GJS, Hirata H, do Carmo LG, Stilhano RS, Ureshino RP, Medaglia NC, Han SW, Churchill G, Bincoletto C, Patel S, Smaili SS. NAADP-sensitive two-pore channels are present and functional in gastric smooth muscle cells. Cell Calcium 2014; 56:51-8. [PMID: 24882212 DOI: 10.1016/j.ceca.2014.04.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 04/11/2014] [Accepted: 04/21/2014] [Indexed: 01/06/2023]
Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) has been identified as an important modulator of Ca(2+) release from the endo-lysosomal system in a variety of cells by a new and ubiquitous class of endo-lysosomal ion channels known as the two-pore channels (TPCs). However, the role of TPCs in NAADP action in smooth muscle is not known. In the present work, we investigated the effects of NAADP in gastric smooth muscle cells and its ability to release Ca(2+) by TPCs. We show that Ca(2+) signals mediated by NAADP were inhibited by disrupting Ca(2+) handling by either acidic organelles (using bafilomycin A1) or the Endoplasmic Reticulum (using thapsigargin, ryanodine or 2-APB). Transcripts for endogenous TPC1 and TPC2 were readily detected and recombinant TPCs localized to the endosomes and/or lysosomes. Overexpression of wild-type TPCs but not pore mutants enhanced NAADP-mediated cytosolic Ca(2+) signals. Desensitizing the NAADP pathway inhibited Ca(2+)-responses to extracellular stimulation with carbachol but not ATP. Taken together, these results indicate that NAADP likely induces Ca(2+) release from the endolysosomal system through TPCs which is subsequently amplified via the ER in an agonist-specific manner. Thus, we suggest a second messenger role for NAADP in smooth muscle cells.
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Affiliation(s)
- Gustavo J S Pereira
- Department of Pharmacology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Hanako Hirata
- Department of Pharmacology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Lúcia G do Carmo
- Department of Pharmacology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Roberta S Stilhano
- Interdisciplinary Center for Gene Therapy, Federal University of São Paulo, São Paulo, Brazil
| | - Rodrigo P Ureshino
- Department of Pharmacology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Natalia C Medaglia
- Department of Pharmacology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Sang W Han
- Interdisciplinary Center for Gene Therapy, Federal University of São Paulo, São Paulo, Brazil
| | - Grant Churchill
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Claudia Bincoletto
- Department of Pharmacology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Soraya S Smaili
- Department of Pharmacology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
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150
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The voltage-gated sodium channel TPC1 confers endolysosomal excitability. Nat Chem Biol 2014; 10:463-9. [PMID: 24776928 DOI: 10.1038/nchembio.1522] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/27/2014] [Indexed: 11/09/2022]
Abstract
The physiological function and molecular regulation of plasma membrane potential have been extensively studied, but how intracellular organelles sense and control membrane potential is not well understood. Using whole-organelle patch clamp recording, we show that endosomes and lysosomes are electrically excitable organelles. In a subpopulation of endolysosomes, a brief electrical stimulus elicits a prolonged membrane potential depolarization spike. The organelles have a previously uncharacterized, depolarization-activated, noninactivating Na(+) channel (lysoNaV). The channel is formed by a two-repeat six-transmembrane-spanning (2×6TM) protein, TPC1, which represents the evolutionary transition between 6TM and 4×6TM voltage-gated channels. Luminal alkalization also opens lysoNaV by markedly shifting the channel's voltage dependence of activation toward hyperpolarization. Thus, TPC1 is a member of a new family of voltage-gated Na(+) channels that senses pH changes and confers electrical excitability to organelles.
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