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Steiner P, Arlt E, Boekhoff I, Gudermann T, Zierler S. TPC Functions in the Immune System. Handb Exp Pharmacol 2023; 278:71-92. [PMID: 36639434 DOI: 10.1007/164_2022_634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Two-pore channels (TPCs) are novel intracellular cation channels, which play a key role in numerous (patho-)physiological and immunological processes. In this chapter, we focus on their function in immune cells and immune reactions. Therefore, we first give an overview of the cellular immune response and the partaking immune cells. Second, we concentrate on ion channels which in the past have been shown to play an important role in the regulation of immune cells. The main focus is then directed to TPCs, which are primarily located in the membranes of acidic organelles, such as lysosomes or endolysosomes but also certain other vesicles. They regulate Ca2+ homeostasis and thus Ca2+ signaling in immune cells. Due to this important functional role, TPCs are enjoying increasing attention within the field of immunology in the last few decades but are also becoming more pertinent as pharmacological targets for the treatment of pro-inflammatory diseases such as allergic hypersensitivity. However, to uncover the precise molecular mechanism of TPCs in immune cell responses, further molecular, genetic, and ultrastructural investigations on TPCs are necessary, which then may pave the way to develop novel therapeutic strategies to treat diseases such as anaphylaxis more specifically.
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Affiliation(s)
- Philip Steiner
- Institute of Pharmacology, Faculty of Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Elisabeth Arlt
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ingrid Boekhoff
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Susanna Zierler
- Institute of Pharmacology, Faculty of Medicine, Johannes Kepler University Linz, Linz, Austria.
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany.
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2
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Abstract
The discovery of NAADP-evoked Ca2+ release in sea urchin eggs and then as a ubiquitous Ca2+ mobilizing messenger has introduced several novel paradigms to our understanding of Ca2+ signalling, not least in providing a link between cell stimulation and Ca2+ release from lysosomes and other acidic Ca2+ storage organelles. In addition, the hallmark concentration-response relationship of NAADP-mediated Ca2+ release, shaped by striking activation/desensitization mechanisms, influences its actions as an intracellular messenger. There has been recent progress in our understanding of the molecular mechanisms underlying NAADP-evoked Ca2+ release, such as the identification of the endo-lysosomal two-pore channel family of cation channels (TPCs) as their principal target and the identity of NAADP-binding proteins that complex with them. The NAADP/TPC signalling axis has gained recent prominence in pathophysiology for their roles in such disease processes as neurodegeneration, tumorigenesis and cellular viral entry.
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Affiliation(s)
- Antony Galione
- Department of Pharmacology, University of Oxford, Oxford, UK.
| | - Lianne C Davis
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Lora L Martucci
- Department of Pharmacology, University of Oxford, Oxford, UK
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3
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Skelding KA, Barry DL, Theron DZ, Lincz LF. Targeting the two-pore channel 2 in cancer progression and metastasis. EXPLORATION OF TARGETED ANTI-TUMOR THERAPY 2022; 3:62-89. [PMID: 36046356 PMCID: PMC9400767 DOI: 10.37349/etat.2022.00072] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 02/02/2022] [Indexed: 11/19/2022] Open
Abstract
The importance of Ca2+ signaling, and particularly Ca2+ channels, in key events of cancer cell function such as proliferation, metastasis, autophagy and angiogenesis, has recently begun to be appreciated. Of particular note are two-pore channels (TPCs), a group of recently identified Ca2+-channels, located within the endolysosomal system. TPC2 has recently emerged as an intracellular ion channel of significant pathophysiological relevance, specifically in cancer, and interest in its role as an anti-cancer drug target has begun to be explored. Herein, an overview of the cancer-related functions of TPC2 and a discussion of its potential as a target for therapeutic intervention, including a summary of clinical trials examining the TPC2 inhibitors, naringenin, tetrandrine, and verapamil for the treatment of various cancers is provided.
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Affiliation(s)
- Kathryn A. Skelding
- Cancer Cell Biology Research Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Callaghan, New South Wales 2308, Australia;Hunter Medical Research Institute, New Lambton Heights, New South Wales 2305, Australia
| | - Daniel L. Barry
- Cancer Cell Biology Research Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Callaghan, New South Wales 2308, Australia;Hunter Medical Research Institute, New Lambton Heights, New South Wales 2305, Australia
| | - Danielle Z. Theron
- Cancer Cell Biology Research Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Callaghan, New South Wales 2308, Australia;Hunter Medical Research Institute, New Lambton Heights, New South Wales 2305, Australia
| | - Lisa F. Lincz
- Cancer Cell Biology Research Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Callaghan, New South Wales 2308, Australia;Hunter Medical Research Institute, New Lambton Heights, New South Wales 2305, Australia;Hunter Hematology Research Group, Calvary Mater Newcastle Hospital, Waratah, New South Wales 2298, Australia
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4
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Martinelli A, Rice ML, Talcott JB, Diaz R, Smith S, Raza MH, Snowling MJ, Hulme C, Stein J, Hayiou-Thomas ME, Hawi Z, Kent L, Pitt SJ, Newbury DF, Paracchini S. A rare missense variant in the ATP2C2 gene is associated with language impairment and related measures. Hum Mol Genet 2021; 30:1160-1171. [PMID: 33864365 PMCID: PMC8188402 DOI: 10.1093/hmg/ddab111] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 01/02/2023] Open
Abstract
At least 5% of children present unexpected difficulties in expressing and understanding spoken language. This condition is highly heritable and often co-occurs with other neurodevelopmental disorders such as dyslexia and ADHD. Through an exome sequencing analysis, we identified a rare missense variant (chr16:84405221, GRCh38.p12) in the ATP2C2 gene. ATP2C2 was implicated in language disorders by linkage and association studies, and exactly the same variant was reported previously in a different exome sequencing study for language impairment (LI). We followed up this finding by genotyping the mutation in cohorts selected for LI and comorbid disorders. We found that the variant had a higher frequency in LI cases (1.8%, N = 360) compared with cohorts selected for dyslexia (0.8%, N = 520) and ADHD (0.7%, N = 150), which presented frequencies comparable to reference databases (0.9%, N = 24 046 gnomAD controls). Additionally, we observed that carriers of the rare variant identified from a general population cohort (N = 42, ALSPAC cohort) presented, as a group, lower scores on a range of reading and language-related measures compared to controls (N = 1825; minimum P = 0.002 for non-word reading). ATP2C2 encodes for an ATPase (SPCA2) that transports calcium and manganese ions into the Golgi lumen. Our functional characterization suggested that the rare variant influences the ATPase activity of SPCA2. Thus, our results further support the role of ATP2C2 locus in language-related phenotypes and pinpoint the possible effects of a specific rare variant at molecular level.
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Affiliation(s)
| | - Mabel L Rice
- Child Language Doctoral Program, University of Kansas, Lawrence, KS, USA
| | - Joel B Talcott
- Aston Brain Centre, School of Life and Health Sciences, Aston University, Birmingham, UK
| | - Rebeca Diaz
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Shelley Smith
- Department of Neurological Sciences, University of Nebraska Medical Center, Lincoln, NE, USA
| | | | - Margaret J Snowling
- Department of Experimental Psychology and St John's College, University of Oxford, Oxford, UK
| | - Charles Hulme
- Department of Education, University of Oxford, Oxford, UK
| | - John Stein
- Department of Physiology, University of Oxford, Oxford, UK
| | | | - Ziarih Hawi
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Lindsey Kent
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Samantha J Pitt
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Dianne F Newbury
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
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5
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Negri S, Faris P, Moccia F. Endolysosomal Ca 2+ signaling in cardiovascular health and disease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 363:203-269. [PMID: 34392930 DOI: 10.1016/bs.ircmb.2021.03.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
An increase in intracellular Ca2+ concentration ([Ca2+]i) regulates a plethora of functions in the cardiovascular (CV) system, including contraction in cardiomyocytes and vascular smooth muscle cells (VSMCs), and angiogenesis in vascular endothelial cells and endothelial colony forming cells. The sarco/endoplasmic reticulum (SR/ER) represents the largest endogenous Ca2+ store, which releases Ca2+ through ryanodine receptors (RyRs) and/or inositol-1,4,5-trisphosphate receptors (InsP3Rs) upon extracellular stimulation. The acidic vesicles of the endolysosomal (EL) compartment represent an additional endogenous Ca2+ store, which is targeted by several second messengers, including nicotinic acid adenine dinucleotide phosphate (NAADP) and phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2], and may release intraluminal Ca2+ through multiple Ca2+ permeable channels, including two-pore channels 1 and 2 (TPC1-2) and Transient Receptor Potential Mucolipin 1 (TRPML1). Herein, we discuss the emerging, pathophysiological role of EL Ca2+ signaling in the CV system. We describe the role of cardiac TPCs in β-adrenoceptor stimulation, arrhythmia, hypertrophy, and ischemia-reperfusion injury. We then illustrate the role of EL Ca2+ signaling in VSMCs, where TPCs promote vasoconstriction and contribute to pulmonary artery hypertension and atherosclerosis, whereas TRPML1 sustains vasodilation and is also involved in atherosclerosis. Subsequently, we describe the mechanisms whereby endothelial TPCs promote vasodilation, contribute to neurovascular coupling in the brain and stimulate angiogenesis and vasculogenesis. Finally, we discuss about the possibility to target TPCs, which are likely to mediate CV cell infection by the Severe Acute Respiratory Disease-Coronavirus-2, with Food and Drug Administration-approved drugs to alleviate the detrimental effects of Coronavirus Disease-19 on the CV system.
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Affiliation(s)
- Sharon Negri
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Pawan Faris
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Francesco Moccia
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy.
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6
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Morgan AJ, Davis LC, Galione A. Choreographing endo-lysosomal Ca 2+ throughout the life of a phagosome. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119040. [PMID: 33872669 DOI: 10.1016/j.bbamcr.2021.119040] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/05/2021] [Accepted: 04/07/2021] [Indexed: 12/20/2022]
Abstract
The emergence of endo-lysosomes as ubiquitous Ca2+ stores with their unique cohort of channels has resulted in their being implicated in a growing number of processes in an ever-increasing number of cell types. The architectural and regulatory constraints of these acidic Ca2+ stores distinguishes them from other larger Ca2+ sources such as the ER and influx across the plasma membrane. In view of recent advances in the understanding of the modes of operation, we discuss phagocytosis as a template for how endo-lysosomal Ca2+ signals (generated via TPC and TRPML channels) can be integrated in multiple sophisticated ways into biological processes. Phagocytosis illustrates how different endo-lysosomal Ca2+ signals drive different phases of a process, and how these can be altered by disease or infection.
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Affiliation(s)
- Anthony J Morgan
- Department of Pharmacology, University of Oxford, Mansfield Park, Oxford OX1 3QT, UK.
| | - Lianne C Davis
- Department of Pharmacology, University of Oxford, Mansfield Park, Oxford OX1 3QT, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Park, Oxford OX1 3QT, UK.
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7
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Westman J, Freeman SA, Grinstein S. Unconventional role of lysosomes in phagocytosis. Cell Calcium 2020; 91:102269. [PMID: 32818767 DOI: 10.1016/j.ceca.2020.102269] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 08/10/2020] [Indexed: 12/24/2022]
Abstract
Lysosomes are generally thought to be required only for the late stages of phagosome maturation, providing the proton pumps (V-ATPases) and hydrolases needed to acidify and degrade the ingested prey. A recent paper by Davis et al. (EMBO J. [2020], doi:10.15252/embj.2019104058) reports the involvement of lysosomes at a much earlier stage, namely in scission of phagosomes from the plasma membrane. Here we analyze these findings, highlighting a number of unexpected observations and unresolved questions.
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Affiliation(s)
- Johannes Westman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON, M5G 0A4, Canada
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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8
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Davis LC, Morgan AJ, Galione A. NAADP-regulated two-pore channels drive phagocytosis through endo-lysosomal Ca 2+ nanodomains, calcineurin and dynamin. EMBO J 2020; 39:e104058. [PMID: 32510172 PMCID: PMC7360967 DOI: 10.15252/embj.2019104058] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 04/22/2020] [Accepted: 04/29/2020] [Indexed: 12/15/2022] Open
Abstract
Macrophages clear pathogens by phagocytosis and lysosomes that fuse with phagosomes are traditionally regarded as to a source of membranes and luminal degradative enzymes. Here, we reveal that endo-lysosomes act as platforms for a new phagocytic signalling pathway in which FcγR activation recruits the second messenger NAADP and thereby promotes the opening of Ca2+ -permeable two-pore channels (TPCs). Remarkably, phagocytosis is driven by these local endo-lysosomal Ca2+ nanodomains rather than global cytoplasmic or ER Ca2+ signals. Motile endolysosomes contact nascent phagosomes to promote phagocytosis, whereas endo-lysosome immobilization prevents it. We show that TPC-released Ca2+ rapidly activates calcineurin, which in turn dephosphorylates and activates the GTPase dynamin-2. Finally, we find that different endo-lysosomal Ca2+ channels play diverse roles, with TPCs providing a universal phagocytic signal for a wide range of particles and TRPML1 being only required for phagocytosis of large targets.
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Affiliation(s)
- Lianne C Davis
- Department of Pharmacology, University of Oxford, Oxford, UK
| | | | - Antony Galione
- Department of Pharmacology, University of Oxford, Oxford, UK
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9
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Abstract
Of the established Ca2+-mobilizing messengers, NAADP is arguably the most tantalizing. It is the most potent, often efficacious at low nanomolar concentrations, and its receptors undergo dramatic desensitization. Recent studies have identified a new class of calcium-release channel, the two-pore channels (TPCs), as the likely targets for NAADP regulation, even though the effect may be indirect. These channels localized at endolysosomes, where they mediate local Ca2+ release, and have highlighted a new role of acidic organelles as targets for messenger-evoked Ca2+ mobilization. Three distinct roles of TPCs have been identified. The first is to effect local Ca2+ release that may play a role in endolysosomal function including vesicular fusion and trafficking. The second is to trigger global calcium release by recruiting Ca2+-induced Ca2+-release (CICR) channels at lysosomal-endoplasmic reticulum (ER) junctions. The third is to regulate plasma membrane excitability by the targeting of Ca2+ release from appropriately positioned subplasma membrane stores to regulate plasma membrane Ca2+-activated channels. In this review, I discuss the role of nicotinic acid adenine nucleotide diphosphate (NAADP)-mediated Ca2+ release from endolysosomal stores as a widespread trigger for intracellular calcium signaling mechanisms, and how studies of TPCs are beginning to enhance our understanding of the central role of lysosomes in Ca2+ signaling.
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Affiliation(s)
- Antony Galione
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom
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10
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Krogsaeter EK, Biel M, Wahl-Schott C, Grimm C. The protein interaction networks of mucolipins and two-pore channels. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2019; 1866:1111-1123. [PMID: 30395881 PMCID: PMC7111325 DOI: 10.1016/j.bbamcr.2018.10.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/24/2018] [Accepted: 10/26/2018] [Indexed: 12/11/2022]
Abstract
BACKGROUND The endolysosomal, non-selective cation channels, two-pore channels (TPCs) and mucolipins (TRPMLs), regulate intracellular membrane dynamics and autophagy. While partially compensatory for each other, isoform-specific intracellular distribution, cell-type expression patterns, and regulatory mechanisms suggest different channel isoforms confer distinct properties to the cell. SCOPE OF REVIEW Briefly, established TPC/TRPML functions and interaction partners ('interactomes') are discussed. Novel TRPML3 interactors are shown, and a meta-analysis of experimentally obtained channel interactomes conducted. Accordingly, interactomes are compared and contrasted, and subsequently described in detail for TPC1, TPC2, TRPML1, and TRPML3. MAJOR CONCLUSIONS TPC interactomes are well-defined, encompassing intracellular membrane organisation proteins. TRPML interactomes are varied, encompassing cardiac contractility- and chaperone-mediated autophagy proteins, alongside regulators of intercellular signalling. GENERAL SIGNIFICANCE Comprising recently proposed targets to treat cancers, infections, metabolic disease and neurodegeneration, the advancement of TPC/TRPML understanding is of considerable importance. This review proposes novel directions elucidating TPC/TRPML relevance in health and disease. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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Affiliation(s)
- Einar K Krogsaeter
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Munich (LMU) Nussbaumstrasse 26, 80336 Munich
| | - Martin Biel
- Department of Pharmacy - Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Germany
| | - Christian Wahl-Schott
- Hannover Medical School, Institute for Neurophysiology, OE 4230, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Christian Grimm
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Munich (LMU) Nussbaumstrasse 26, 80336 Munich.
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11
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Endolysosomal Ca 2+ Signalling and Cancer Hallmarks: Two-Pore Channels on the Move, TRPML1 Lags Behind! Cancers (Basel) 2018; 11:cancers11010027. [PMID: 30591696 PMCID: PMC6356888 DOI: 10.3390/cancers11010027] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 12/21/2018] [Accepted: 12/21/2018] [Indexed: 12/22/2022] Open
Abstract
The acidic vesicles of the endolysosomal (EL) system are emerging as an intracellular Ca2+ store implicated in the regulation of multiple cellular functions. The EL Ca2+ store releases Ca2+ through a variety of Ca2+-permeable channels, including Transient Receptor Potential (TRP) Mucolipin 1-3 (TRPML1-3) and two-pore channels 1-2 (TPC1-2), whereas EL Ca2+ refilling is sustained by the proton gradient across the EL membrane and/or by the endoplasmic reticulum (ER). EL Ca2+ signals may be either spatially restricted to control vesicle trafficking, autophagy and membrane repair or may be amplified into a global Ca2+ signal through the Ca2+-dependent recruitment of ER-embedded channels. Emerging evidence suggested that nicotinic acid adenine dinucleotide phosphate (NAADP)-gated TPCs sustain multiple cancer hallmarks, such as migration, invasiveness and angiogenesis. Herein, we first survey the EL Ca2+ refilling and release mechanisms and then focus on the oncogenic role of EL Ca2+ signaling. While the evidence in favor of TRPML1 involvement in neoplastic transformation is yet to be clearly provided, TPCs are emerging as an alternative target for anticancer therapies.
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12
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Foster WJ, Taylor HBC, Padamsey Z, Jeans AF, Galione A, Emptage NJ. Hippocampal mGluR1-dependent long-term potentiation requires NAADP-mediated acidic store Ca 2+ signaling. Sci Signal 2018; 11:11/558/eaat9093. [PMID: 30482851 DOI: 10.1126/scisignal.aat9093] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Acidic organelles, such as endosomes and lysosomes, store Ca2+ that is released in response to intracellular increases in the second messenger nicotinic acid adenine dinucleotide phosphate (NAADP). In neurons, NAADP and Ca2+ signaling contribute to synaptic plasticity, a process of activity-dependent long-term potentiation (LTP) [or, alternatively, long-term depression (LTD)] of synaptic strength and neuronal transmission that is critical for neuronal function and memory formation. We explored the function of and mechanisms regulating acidic Ca2+ store signaling in murine hippocampal neurons. We found that metabotropic glutamate receptor 1 (mGluR1) was coupled to NAADP signaling that elicited Ca2+ release from acidic stores. In turn, this released Ca2+-mediated mGluR1-dependent LTP by transiently inhibiting SK-type K+ channels, possibly through the activation of protein phosphatase 2A. Genetically removing two-pore channels (TPCs), which are endolysosomal-specific ion channels, switched the polarity of plasticity from LTP to LTD, indicating the importance of specific receptor store coupling and providing mechanistic insight into how mGluR1 can produce both synaptic potentiation and synaptic depression.
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Affiliation(s)
- William J Foster
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Henry B C Taylor
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Zahid Padamsey
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Alexander F Jeans
- 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.
| | - Nigel J Emptage
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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13
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Two-pore channels and disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1678-1686. [PMID: 29746898 PMCID: PMC6162333 DOI: 10.1016/j.bbamcr.2018.05.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 05/03/2018] [Indexed: 01/25/2023]
Abstract
Two-pore channels (TPCs) are Ca2+-permeable endo-lysosomal ion channels subject to multi-modal regulation. They mediate their physiological effects through releasing Ca2+ from acidic organelles in response to cues such as the second messenger, NAADP. Here, we review emerging evidence linking TPCs to disease. We discuss how perturbing both local and global Ca2+ changes mediated by TPCs through chemical and/or molecular manipulations can induce or reverse disease phenotypes. We cover evidence from models of Parkinson's disease, non-alcoholic fatty liver disease, Ebola infection, cancer, cardiac dysfunction and diabetes. A need for more drugs targeting TPCs is identified.
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14
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Patel S, Churamani D, Brailoiu E. NAADP-evoked Ca 2+ signals through two-pore channel-1 require arginine residues in the first S4-S5 linker. Cell Calcium 2017; 68:1-4. [PMID: 29129203 PMCID: PMC5700777 DOI: 10.1016/j.ceca.2017.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 09/27/2017] [Accepted: 09/27/2017] [Indexed: 12/11/2022]
Abstract
The S4–S5 linker of TPCs harbours conserved basic residues. Arginine residues in the S4–S5 linker are required for activation of TPC1 by NAADP. The S4–S5 linker emerges as a potential common determinant for TPC activation.
Two-pore channels (TPCs) are two-domain members of the voltage-gated ion channel superfamily that localize to acidic organelles. Their mechanism of activation (ligands such as NAADP/PI(3,5)P2 versus voltage) and ion selectivity (Ca2+ versus Na+) is debated. Here we report that a cluster of arginine residues in the first domain required for selective voltage-gating of TPC1 map not to the voltage-sensing fourth transmembrane region (S4) but to a cytosolic downstream region (S4-S5 linker). These residues are conserved between TPC isoforms suggesting a generic role in TPC activation. Accordingly, mutation of residues in TPC1 but not the analogous region in the second domain prevents Ca2+ release by NAADP in intact cells. Our data affirm the role of TPCs in NAADP-mediated Ca2+ signalling and unite differing models of channel activation through identification of common domain-specific residues.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK.
| | - Dev Churamani
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Eugen Brailoiu
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
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15
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Castonguay J, Orth JHC, Müller T, Sleman F, Grimm C, Wahl-Schott C, Biel M, Mallmann RT, Bildl W, Schulte U, Klugbauer N. The two-pore channel TPC1 is required for efficient protein processing through early and recycling endosomes. Sci Rep 2017; 7:10038. [PMID: 28855648 PMCID: PMC5577145 DOI: 10.1038/s41598-017-10607-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/11/2017] [Indexed: 02/06/2023] Open
Abstract
Two-pore channels (TPCs) are localized in endo-lysosomal compartments and assumed to play an important role for vesicular fusion and endosomal trafficking. Recently, it has been shown that both TPC1 and 2 were required for host cell entry and pathogenicity of Ebola viruses. Here, we investigate the cellular function of TPC1 using protein toxins as model substrates for distinct endosomal processing routes. Toxin uptake and activation through early endosomes but not processing through other compartments were reduced in TPC1 knockout cells. Detailed co-localization studies with subcellular markers confirmed predominant localization of TPC1 to early and recycling endosomes. Proteomic analysis of native TPC1 channels finally identified direct interaction with a distinct set of syntaxins involved in fusion of intracellular vesicles. Together, our results demonstrate a general role of TPC1 for uptake and processing of proteins in early and recycling endosomes, likely by providing high local Ca2+ concentrations required for SNARE-mediated vesicle fusion.
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Affiliation(s)
- Jan Castonguay
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, Albert-Ludwigs-University, Albertstrasse 25, 79104, Freiburg, Germany
| | - Joachim H C Orth
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, Albert-Ludwigs-University, Albertstrasse 25, 79104, Freiburg, Germany
| | - Thomas Müller
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, Albert-Ludwigs-University, Albertstrasse 25, 79104, Freiburg, Germany
| | - Faten Sleman
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, Albert-Ludwigs-University, Albertstrasse 25, 79104, Freiburg, Germany
| | - Christian Grimm
- Department of Pharmacy, Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-University, Munich, Germany
| | - Christian Wahl-Schott
- Department of Pharmacy, Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-University, Munich, Germany
| | - Martin Biel
- Department of Pharmacy, Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-University, Munich, Germany
| | - Robert Theodor Mallmann
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, Albert-Ludwigs-University, Albertstrasse 25, 79104, Freiburg, Germany
| | - Wolfgang Bildl
- Institute of Physiology II, Faculty of Medicine, Albert-Ludwigs-University, Hermann-Herder-Strasse 7, 79104, Freiburg, Germany
| | - Uwe Schulte
- Institute of Physiology II, Faculty of Medicine, Albert-Ludwigs-University, Hermann-Herder-Strasse 7, 79104, Freiburg, Germany.,Logopharm GmbH, Schlossstrasse 14, 79232, March-Buchheim, Germany.,Center for Biological Signaling Studies (BIOSS), Schänzlestrasse 18, 79104, Freiburg, Germany
| | - Norbert Klugbauer
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, Albert-Ludwigs-University, Albertstrasse 25, 79104, Freiburg, Germany.
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16
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Kintzer AF, Stroud RM. On the structure and mechanism of two-pore channels. FEBS J 2017; 285:233-243. [PMID: 28656706 DOI: 10.1111/febs.14154] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/24/2017] [Accepted: 06/23/2017] [Indexed: 12/22/2022]
Abstract
In eukaryotes, two-pore channels (TPC1-3) comprise a family of ion channels that regulate the conductance of Na+ and Ca2+ ions across cellular membranes. TPC1-3 form endolysosomal channels, but TPC3 can also function in the plasma membrane. TPC1/3 are voltage-gated channels, but TPC2 opens in response to binding endolysosome-specific lipid phosphatidylinositol-3,5-diphosphate (PI(3,5)P2 ). Filoviruses, such as Ebola, exploit TPC-mediated ion release as a means of escape from the endolysosome during infection. Antagonists that block TPC1/2 channel conductance abrogate filoviral infections. TPC1/2 form complexes with the mechanistic target of rapamycin complex 1 (mTORC1) at the endolysosomal surface that couple cellular metabolic state and cytosolic nutrient concentrations to the control of membrane potential and pH. We determined the X-ray structure of TPC1 from Arabidopsis thaliana (AtTPC1) to 2.87Å resolution-one of the two first reports of a TPC channel structure. Here, we summarize these findings and the implications that the structure may have for understanding endolysosomal control mechanisms and their role in human health.
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Affiliation(s)
- Alexander F Kintzer
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
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17
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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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18
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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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19
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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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20
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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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21
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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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22
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Fan Y, Li X, Zhang Y, Fan X, Zhang N, Zheng H, Song Y, Shen C, Shen J, Ren F, Yang J. Genetic Variants of TPCN2 Associated with Type 2 Diabetes Risk in the Chinese Population. PLoS One 2016; 11:e0149614. [PMID: 26918892 PMCID: PMC4769022 DOI: 10.1371/journal.pone.0149614] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 02/02/2016] [Indexed: 01/06/2023] Open
Abstract
OBJECTIVE The aim of this study was to determine whether TPCN2 genetic variants are associated with type 2 diabetes and to elucidate which variants in TPCN2 confer diabetes susceptibility in the Chinese population. RESEARCH DESIGN AND METHODS The sample population included 384 patients with type 2 diabetes and 1468 controls. Anthropometric parameters, glycemic and lipid profiles and insulin resistance were measured. We selected 6 TPCN2 tag single nucleotide polymorphisms (rs35264875, rs267603153, rs267603154, rs3829241, rs1551305, and rs3750965). Genotypes were determined using a Sequenom MassARRAY SNP genotyping system. RESULTS Ultimately, we genotyped 3 single nucleotide polymorphisms (rs3750965, rs3829241, and rs1551305) in all individuals. There was a 5.1% higher prevalence of the rs1551305 variant allele in type 2 diabetes individuals (A) compared with wild-type homozygous individuals (G). The AA genotype of rs1551305 was associated with a higher diabetes risk (p<0.05). The distributions of rs3829241 and rs3750965 polymorphisms were not significantly different between the two groups. HOMA-%B of subjects harboring the AA genotype of rs1551305 decreased by 14.87% relative to the GG genotype. CONCLUSIONS TPCN2 plays a role in metabolic regulation, and the rs1551305 single nucleotide polymorphism is associated with type 2 diabetes risk. Future work will begin to unravel the underlying mechanisms.
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Affiliation(s)
- Yujuan Fan
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Xuesong Li
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Yu Zhang
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Xiaofang Fan
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Ning Zhang
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Hui Zheng
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Yuping Song
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Chunfang Shen
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Jiayi Shen
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Fengdong Ren
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
| | - Jialin Yang
- Department of Endocrinology, Central Hospital of Minhang District, Minhang Hospital affiliated with Fudan University, Shanghai, People’s Republic of China
- * E-mail:
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23
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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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24
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Ebolavirus Glycoprotein Directs Fusion through NPC1+ Endolysosomes. J Virol 2015; 90:605-10. [PMID: 26468524 PMCID: PMC4702577 DOI: 10.1128/jvi.01828-15] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 10/06/2015] [Indexed: 12/31/2022] Open
Abstract
Ebolavirus, a deadly hemorrhagic fever virus, was thought to enter cells through endolysosomes harboring its glycoprotein receptor, Niemann-Pick C1. However, an alternate model was recently proposed in which ebolavirus enters through a later NPC1-negative endosome that contains two-pore Ca(2+) channel 2 (TPC2), a newly identified ebolavirus entry factor. Here, using live cell imaging, we obtained evidence that in contrast to the new model, ebolavirus enters cells through endolysosomes that contain both NPC1 and TPC2.
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25
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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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26
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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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27
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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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28
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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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29
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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: 130] [Impact Index Per Article: 14.4] [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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30
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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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31
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Evolution of acidic Ca2+ stores and their resident Ca2+-permeable channels. Cell Calcium 2015; 57:222-30. [DOI: 10.1016/j.ceca.2014.12.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/05/2014] [Accepted: 12/09/2014] [Indexed: 11/18/2022]
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32
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Rahman T, Cai X, Brailoiu GC, Abood ME, Brailoiu E, Patel S. Two-pore channels provide insight into the evolution of voltage-gated Ca2+ and Na+ channels. Sci Signal 2014; 7:ra109. [PMID: 25406377 PMCID: PMC4327855 DOI: 10.1126/scisignal.2005450] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Four-domain voltage-gated Ca(2+) and Na(+) channels (CaV, NaV) underpin nervous system function and likely emerged upon intragenic duplication of a primordial two-domain precursor. To investigate if two-pore channels (TPCs) may represent an intermediate in this evolutionary transition, we performed molecular docking simulations with a homology model of TPC1, which suggested that the pore region could bind antagonists of CaV or NaV. CaV or NaV antagonists blocked NAADP (nicotinic acid adenine dinucleotide phosphate)-evoked Ca(2+) signals in sea urchin egg preparations and in intact cells that overexpressed TPC1. By sequence analysis and inspection of the model, we predicted a noncanonical selectivity filter in animal TPCs in which the carbonyl groups of conserved asparagine residues are positioned to coordinate cations. In contrast, a distinct clade of TPCs [TPCR (for TPC-related)] in several unicellular species had ion selectivity filters with acidic residues more akin to CaV. TPCRs were predicted to interact strongly with CaV antagonists. Our data suggest that acquisition of a "blueprint" pharmacological profile and changes in ion selectivity within four-domain voltage-gated ion channels may have predated intragenic duplication of an ancient two-domain ancestor.
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Affiliation(s)
- Taufiq Rahman
- Department of Pharmacology, Cambridge University, Cambridge CB2 1PD, UK.
| | - Xinjiang Cai
- Department of Cell Developmental Biology, University College London, London WC1E 6BT, UK
| | - G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Thomas Jefferson University School of Pharmacy, Philadelphia, PA 19107, USA
| | - Mary E Abood
- Department of Anatomy and Cell Biology and Center for Substance Abuse Research, Temple University, Philadelphia, PA 19140, USA
| | - Eugen Brailoiu
- Department of Pharmacology and Center for Substance Abuse Research, Temple University, Philadelphia, PA 19140, USA
| | - Sandip Patel
- Department of Cell Developmental Biology, University College London, London WC1E 6BT, UK.
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33
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Boccaccio A, Scholz-Starke J, Hamamoto S, Larisch N, Festa M, Gutla PVK, Costa A, Dietrich P, Uozumi N, Carpaneto A. The phosphoinositide PI(3,5)P₂ mediates activation of mammalian but not plant TPC proteins: functional expression of endolysosomal channels in yeast and plant cells. Cell Mol Life Sci 2014; 71:4275-83. [PMID: 24770793 PMCID: PMC11113638 DOI: 10.1007/s00018-014-1623-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/18/2014] [Accepted: 03/31/2014] [Indexed: 11/29/2022]
Abstract
Two-pore channel proteins (TPC) encode intracellular ion channels in both animals and plants. In mammalian cells, the two isoforms (TPC1 and TPC2) localize to the endo-lysosomal compartment, whereas the plant TPC1 protein is targeted to the membrane surrounding the large lytic vacuole. Although it is well established that plant TPC1 channels activate in a voltage- and calcium-dependent manner in vitro, there is still debate on their activation under physiological conditions. Likewise, the mode of animal TPC activation is heavily disputed between two camps favoring as activator either nicotinic acid adenine dinucleotide phosphate (NAADP) or the phosphoinositide PI(3,5)P₂. Here, we investigated TPC current responses to either of these second messengers by whole-vacuole patch-clamp experiments on isolated vacuoles of Arabidopsis thaliana. After expression in mesophyll protoplasts from Arabidopsis tpc1 knock-out plants, we detected the Arabidopsis TPC1-EGFP and human TPC2-EGFP fusion proteins at the membrane of the large central vacuole. Bath (cytosolic) application of either NAADP or PI(3,5)P₂ did not affect the voltage- and calcium-dependent characteristics of AtTPC1-EGFP. By contrast, PI(3,5)P₂ elicited large sodium currents in hTPC2-EGFP-containing vacuoles, while NAADP had no such effect. Analogous results were obtained when PI(3,5)P₂ was applied to hTPC2 expressed in baker's yeast giant vacuoles. Our results underscore the fundamental differences in the mode of current activation and ion selectivity between animal and plant TPC proteins and corroborate the PI(3,5)P₂-mediated activation and Na(+) selectivity of mammalian TPC2.
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Affiliation(s)
- Anna Boccaccio
- Institute of Biophysics, National Research Council, Via De Marini 6, 16149 Genoa, Italy
| | - Joachim Scholz-Starke
- Institute of Biophysics, National Research Council, Via De Marini 6, 16149 Genoa, Italy
| | - Shin Hamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama, Sendai, 980-8579 Japan
| | - Nina Larisch
- Department of Biology, Molecular Plant Physiology and Erlangen Center of Plant Science, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, 91058 Erlangen, Germany
| | - Margherita Festa
- Institute of Biophysics, National Research Council, Via De Marini 6, 16149 Genoa, Italy
| | | | - Alex Costa
- Department of Biology, Università degli Studi di Milano, Via G. Celoria 26, 20133 Milan, Italy
- Milan Division, Institute of Biophysics, National Research Council, Via G. Celoria 26, 20133 Milan, Italy
| | - Petra Dietrich
- Department of Biology, Molecular Plant Physiology and Erlangen Center of Plant Science, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, 91058 Erlangen, Germany
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama, Sendai, 980-8579 Japan
| | - Armando Carpaneto
- Institute of Biophysics, National Research Council, Via De Marini 6, 16149 Genoa, Italy
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34
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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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35
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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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36
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Abstract
Much excitement surrounded the proposal that a family of endo-lysosomal channels, the two-pore channels (TPCs) were the long sought after targets of the Ca(2+) -mobilising messenger, nicotinic acid adenine dinucleotide phosphate (NAADP). However, the role of TPCs in NAADP signalling may be more complex than originally envisaged. First, NAADP may not bind directly to TPCs but via an accessory protein. Second, two papers recently challenged the notion that TPCs are NAADP-regulated Ca(2+) channels by suggesting that they are highly selective Na(+) channels regulated by the lipid phosphatidylinositol 3,5-bisphosphate and by ATP. This paper aims critically to evaluate the evidence for TPCs as NAADP targets and to discuss how the new findings fit in with what we know about endo-lysosomal Ca(2+) stores.
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37
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The N-terminal region of two-pore channel 1 regulates trafficking and activation by NAADP. Biochem J 2013; 453:147-51. [PMID: 23634879 DOI: 10.1042/bj20130474] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
TPCs (two-pore channels) are NAADP (nicotinic acid-adenine dinucleotide phosphate)-sensitive Ca2+-permeable ion channels expressed on acidic organelles. In the present study we show that deletion of the N-terminal region redirects TPC1 to the ER (endoplasmic reticulum). The introduction of fluorophores at the N-terminus of TPC1 does not affect its subcellular location, but does reversibly abolish NAADP sensitivity. Our results reveal a dual role for the N-terminus in localization and function of TPC1.
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38
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Lu Y, Hao BX, Graeff R, Wong CWM, Wu WT, Yue J. Two pore channel 2 (TPC2) inhibits autophagosomal-lysosomal fusion by alkalinizing lysosomal pH. J Biol Chem 2013; 288:24247-63. [PMID: 23836916 PMCID: PMC3745369 DOI: 10.1074/jbc.m113.484253] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Autophagy is an evolutionarily conserved lysosomal degradation pathway, yet the underlying mechanisms remain poorly understood. Nicotinic acid adenine dinucleotide phosphate (NAADP), one of the most potent Ca2+ mobilizing messengers, elicits Ca2+ release from lysosomes via the two pore channel 2 (TPC2) in many cell types. Here we found that overexpression of TPC2 in HeLa or mouse embryonic stem cells inhibited autophagosomal-lysosomal fusion, thereby resulting in the accumulation of autophagosomes. Treatment of TPC2 expressing cells with a cell permeant-NAADP agonist, NAADP-AM, further induced autophagosome accumulation. On the other hand, TPC2 knockdown or treatment of cells with Ned-19, a NAADP antagonist, markedly decreased the accumulation of autophagosomes. TPC2-induced accumulation of autophagosomes was also markedly blocked by ATG5 knockdown. Interestingly, inhibiting mTOR activity failed to increase TPC2-induced autophagosome accumulation. Instead, we found that overexpression of TPC2 alkalinized lysosomal pH, and lysosomal re-acidification abolished TPC2-induced autophagosome accumulation. In addition, TPC2 overexpression had no effect on general endosomal-lysosomal degradation but prevented the recruitment of Rab-7 to autophagosomes. Taken together, our data demonstrate that TPC2/NAADP/Ca2+ signaling alkalinizes lysosomal pH to specifically inhibit the later stage of basal autophagy progression.
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Affiliation(s)
- Yingying Lu
- Department of Physiology, University of Hong Kong, Hong Kong, China
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39
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Zhang ZH, Lu YY, Yue J. Two pore channel 2 differentially modulates neural differentiation of mouse embryonic stem cells. PLoS One 2013; 8:e66077. [PMID: 23776607 PMCID: PMC3680454 DOI: 10.1371/journal.pone.0066077] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 05/01/2013] [Indexed: 12/15/2022] Open
Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is an endogenous Ca2+ mobilizing nucleotide presented in various species. NAADP mobilizes Ca2+ from acidic organelles through two pore channel 2 (TPC2) in many cell types and it has been previously shown that NAADP can potently induce neuronal differentiation in PC12 cells. Here we examined the role of TPC2 signaling in the neural differentiation of mouse embryonic stem (ES) cells. We found that the expression of TPC2 was markedly decreased during the initial ES cell entry into neural progenitors, and the levels of TPC2 gradually rebounded during the late stages of neurogenesis. Correspondingly, TPC2 knockdown accelerated mouse ES cell differentiation into neural progenitors but inhibited these neural progenitors from committing to neurons. Overexpression of TPC2, on the other hand, inhibited mouse ES cell from entering the early neural lineage. Interestingly, TPC2 knockdown had no effect on the differentiation of astrocytes and oligodendrocytes of mouse ES cells. Taken together, our data indicate that TPC2 signaling plays a temporal and differential role in modulating the neural lineage entry of mouse ES cells, in that TPC2 signaling inhibits ES cell entry to early neural progenitors, but is required for late neuronal differentiation.
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Affiliation(s)
- Zhe-Hao Zhang
- Department of Physiology, University of Hong Kong, Hong Kong, China
| | - Ying-Ying Lu
- Department of Physiology, University of Hong Kong, Hong Kong, China
| | - Jianbo Yue
- Department of Physiology, University of Hong Kong, Hong Kong, China
- * E-mail:
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40
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Abstract
NAADP is a potent Ca2+ mobilizing messenger [1-3]. Since its discovery in 1995 [4] a considerable volume of literature has shown that NAADP couples cell stimulation to endolysosomal Ca2+ release and thereby the regulation of many cellular functions [5]. However definition of its molecular mechanism of action has proved far from easy. Since 2009, a consensus emerged as several independent groups coalesced upon the two-pore channel (TPC) family as NAADP-activated channels essential for Ca2+ release from endolysosomal Ca2+ stores [6-8]. However this view has been recently challenged by data clearly showing that TPCs function as Na+-selective channels apparently insensitive to NAADP [9;10]. Given the two fundamental characteristics defining an ion channel comprise the opening stimulus and the nature of the permeant ions, scrutiny of these seeming irreconcilable viewpoints is essential. The purpose of this commentary is to distil the remaining consensus while interrogating these divergent viewpoints. From this analysis, critical experimental needs are identified.
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Affiliation(s)
- 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, London, UK
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41
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Neely Kayala KM, Dickinson GD, Minassian A, Walls KC, Green KN, Laferla FM. Presenilin-null cells have altered two-pore calcium channel expression and lysosomal calcium: implications for lysosomal function. Brain Res 2012; 1489:8-16. [PMID: 23103503 DOI: 10.1016/j.brainres.2012.10.036] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/10/2012] [Accepted: 10/19/2012] [Indexed: 01/01/2023]
Abstract
Presenilins are necessary for calcium homeostasis and also for efficient proteolysis through the autophagy/lysosome system. Presenilin regulates both endoplasmic reticulum calcium stores and autophagic proteolysis in a γ-secretase independent fashion. The endo-lysosome system can also act as a calcium store, with calcium efflux channels being recently identified as two-pore channels 1 and 2. Here we investigated lysosomal calcium content and the channels that mediate calcium release from these acidic stores in presenilin knockout cells. We report that presenilin loss leads to a lower total lysosomal calcium store despite the buildup of lysosomes found in these cells. Additionally, we find alterations in two-pore calcium channel protein expression, with loss of presenilin preventing the formation of a high molecular weight species of TPC1 and TPC2. Finally, we find that treatments that disturb lysosomal calcium release lead to a reduction in autophagy function yet lysosomal inhibitors do not alter two-pore calcium channel expression. These data indicate that alterations in lysosomal calcium in the absence of presenilins might be leading to disruptions in autophagy.
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Affiliation(s)
- Kara M Neely Kayala
- Department of Neurobiology and Behavior, University of California, Irvine, 3208 Biological Sciences III, Irvine, CA 92697-4545, United States
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42
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Marchant JS, Lin-Moshier Y, Walseth TF, Patel S. The Molecular Basis for Ca 2+ Signalling by NAADP: Two-Pore Channels in a Complex? ACTA ACUST UNITED AC 2012; 1:63-76. [PMID: 25309835 DOI: 10.1166/msr.2012.1003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
NAADP is a potent Ca2+ mobilizing messenger in a variety of cells but its molecular mechanism of action is incompletely understood. Accumulating evidence indicates that the poorly characterized two-pore channels (TPCs) in animals are NAADP sensitive Ca2+-permeable channels. TPCs localize to the endo-lysosomal system but are functionally coupled to the better characterized endoplasmic reticulum Ca2+ channels to generate physiologically relevant complex Ca2+ signals. Whether TPCs directly bind NAADP is not clear. Here we discuss the idea based on recent studies that TPCs are the pore-forming subunits of a protein complex that includes tightly associated, low molecular weight NAADP-binding proteins.
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Affiliation(s)
- Jonathan S Marchant
- Department of Pharmacology, University of Minnesota Medical School, MN 55455, USA
| | - Yaping Lin-Moshier
- Department of Pharmacology, University of Minnesota Medical School, MN 55455, USA
| | - Timothy F Walseth
- Department of Pharmacology, University of Minnesota Medical School, MN 55455, USA
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, WC1E 6BT, UK
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43
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Larisch N, Schulze C, Galione A, Dietrich P. An N-Terminal Dileucine Motif Directs Two-Pore Channels to the Tonoplast of Plant Cells. Traffic 2012; 13:1012-22. [DOI: 10.1111/j.1600-0854.2012.01366.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 04/06/2012] [Accepted: 04/10/2012] [Indexed: 12/23/2022]
Affiliation(s)
- Nina Larisch
- Department Biology; Friedrich-Alexander-Universität Erlangen-Nürnberg, Molecular Plant Physiology and Erlangen Center of Plant Science; Staudtstrasse 5; 91058; Erlangen; Germany
| | - Christina Schulze
- Department Biology; Friedrich-Alexander-Universität Erlangen-Nürnberg, Molecular Plant Physiology and Erlangen Center of Plant Science; Staudtstrasse 5; 91058; Erlangen; Germany
| | - Antony Galione
- Department of Pharmacology; Oxford University; Oxford; OX1 3QT; UK
| | - Petra Dietrich
- Department Biology; Friedrich-Alexander-Universität Erlangen-Nürnberg, Molecular Plant Physiology and Erlangen Center of Plant Science; Staudtstrasse 5; 91058; Erlangen; Germany
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Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent Ca(2+)-releasing second messenger that might regulate different ion channels, including the ryanodine receptor, two-pore channels, and TRP-ML1 (transient receptor potential channel, subtype mucolipin 1), a Ca(2+) channel localized to lysosomes. New evidence suggests that a 22- and 23-kilodalton pair of proteins could be the receptor for NAADP. Labeling of NAADP binding proteins was independent of overexpression or knockout of two-pore channels, indicating that two-pore channels, although regulated by NAADP, are not the NAADP receptors. I propose that NAADP binding proteins could bind to different ion channels and thus may explain how NAADP regulates diverse ion channels.
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Affiliation(s)
- Andreas H Guse
- The Calcium Signalling Group, Department of Biochemistry and Signal Transduction, Centre of Experimental Medicine, University Medical Centre Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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Grimm C, Hassan S, Wahl-Schott C, Biel M. Role of TRPML and two-pore channels in endolysosomal cation homeostasis. J Pharmacol Exp Ther 2012; 342:236-44. [PMID: 22518024 DOI: 10.1124/jpet.112.192880] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The transient receptor potential (TRP) channels TRPML1, TRPML2, and TRPML3 (also called mucolipins 1-3 or MCOLN1-3) are nonselective cation channels. Mutations in the Trpml1 gene cause mucolipidosis type IV in humans with clinical features including psychomotor retardation, corneal clouding, and retinal degeneration, whereas mutations in the Trpml3 gene cause deafness, circling behavior, and coat color dilution in mice. No disease-causing mutations are reported for the Trpml2 gene. Like TRPML channels, which are expressed in the endolysosomal pathway, two-pore channels (TPCs), namely TPC1, TPC2, and TPC3, are found in intracellular organelles, in particular in endosomes and lysosomes. Both TRPML channels and TPCs may function as calcium/cation release channels in endosomes, lysosomes, and lysosome-related organelles with TRPMLs being activated by phosphatidylinositol 3,5-bisphosphate and regulated by pH and TPCs being activated by nicotinic acid adenine dinucleotide phosphate in a calcium- and pH-dependent manner. They may also be involved in endolysosomal transport and fusion processes, e.g., as intracellular calcium sources. Currently, however, the exact physiological roles of TRPML channels and TPCs remain quite elusive, and whether TRPML channels are purely endolysosomal ion channels or whether they may also be functionally active at the plasma membrane in vivo remains to be determined.
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Affiliation(s)
- Christian Grimm
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, 81377 Germany.
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46
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Rybalchenko V, Ahuja M, Coblentz J, Churamani D, Patel S, Kiselyov K, Muallem S. Membrane potential regulates nicotinic acid adenine dinucleotide phosphate (NAADP) dependence of the pH- and Ca2+-sensitive organellar two-pore channel TPC1. J Biol Chem 2012; 287:20407-16. [PMID: 22500018 DOI: 10.1074/jbc.m112.359612] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent second messenger that mobilizes Ca(2+) from the acidic endolysosomes by activation of the two-pore channels TPC1 and TPC2. The channel properties of human TPC1 have not been studied before, and its cellular function is not known. In the present study, we characterized TPC1 incorporated into lipid bilayers. The native and recombinant TPC1 channels are activated by NAADP. TPC1 activity requires acidic luminal pH and high luminal Ca(2+). With Ba(2+) as the permeable ion, luminal Ca(2+) activates TPC1 with an apparent K(m) of 180 μm. TPC1 operates in two tightly coupled conductance states of 47 ± 8 and 200 ± 9 picosiemens. Importantly, opening of the large conductance markedly increases the small conductance mean open time. Changes in membrane potential from 0 to -60 mV increased linearly both the small and the large conductances and NP(o), indicating that TPC1 is regulated by voltage. Intriguingly, the apparent affinity for activation of TPC1 by its ligand NAADP is not constant. Rather, hyperpolarization increases the apparent affinity of TPC1 for NAADP by 10 nm/mV. The concerted regulation of TPC1 activity by luminal Ca(2+) and by membrane potential thus provides a potential mechanism to explain NAADP-induced Ca(2+) oscillations. These findings reveal unique properties of TPC1 to explain its role in Ca(2+) oscillations and cell function.
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Affiliation(s)
- Volodymyr Rybalchenko
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, USA
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Walseth TF, Lin-Moshier Y, Jain P, Ruas M, Parrington J, Galione A, Marchant JS, Slama JT. Photoaffinity labeling of high affinity nicotinic acid adenine dinucleotide phosphate (NAADP)-binding proteins in sea urchin egg. J Biol Chem 2011; 287:2308-15. [PMID: 22117077 PMCID: PMC3268392 DOI: 10.1074/jbc.m111.306563] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a messenger that regulates calcium release from intracellular acidic stores. Recent studies have identified two-pore channels (TPCs) as endolysosomal channels that are regulated by NAADP; however, the nature of the NAADP receptor binding site is unknown. To further study NAADP binding sites, we have synthesized and characterized [32P-5-azido]nicotinic acid adenine dinucleotide phosphate ([32P-5N3]NAADP) as a photoaffinity probe. Photolysis of sea urchin egg homogenates preincubated with [32P-5N3]NAADP resulted in specific labeling of 45-, 40-, and 30-kDa proteins, which was prevented by inclusion of nanomolar concentrations of unlabeled NAADP or 5N3-NAADP, but not by micromolar concentrations of structurally related nucleotides such as NAD, nicotinic acid adenine dinucleotide, nicotinamide mononucleotide, nicotinic acid, or nicotinamide. [32P-5N3]NAADP binding was saturable and displayed high affinity (Kd ∼10 nm) in both binding and photolabeling experiments. [32P-5N3]NAADP photolabeling was irreversible in a high K+ buffer, a hallmark feature of NAADP binding in the egg system. The proteins photolabeled by [32P-5N3]NAADP have molecular masses smaller than the sea urchin TPCs, and antibodies to TPCs do not detect any immunoreactivity that comigrates with either the 45-kDa or the 40-kDa photolabeled proteins. Interestingly, antibodies to TPC1 and TPC3 were able to immunoprecipitate a small fraction of the 45- and 40-kDa photolabeled proteins, suggesting that these proteins associate with TPCs. These data suggest that high affinity NAADP binding sites are distinct from TPCs.
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Affiliation(s)
- Timothy F Walseth
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
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