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Hu M, Feng X, Liu Q, Liu S, Huang F, Xu H. The ion channels of endomembranes. Physiol Rev 2024; 104:1335-1385. [PMID: 38451235 DOI: 10.1152/physrev.00025.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 02/20/2024] [Accepted: 02/25/2024] [Indexed: 03/08/2024] Open
Abstract
The endomembrane system consists of organellar membranes in the biosynthetic pathway [endoplasmic reticulum (ER), Golgi apparatus, and secretory vesicles] as well as those in the degradative pathway (early endosomes, macropinosomes, phagosomes, autophagosomes, late endosomes, and lysosomes). These endomembrane organelles/vesicles work together to synthesize, modify, package, transport, and degrade proteins, carbohydrates, and lipids, regulating the balance between cellular anabolism and catabolism. Large ion concentration gradients exist across endomembranes: Ca2+ gradients for most endomembrane organelles and H+ gradients for the acidic compartments. Ion (Na+, K+, H+, Ca2+, and Cl-) channels on the organellar membranes control ion flux in response to cellular cues, allowing rapid informational exchange between the cytosol and organelle lumen. Recent advances in organelle proteomics, organellar electrophysiology, and luminal and juxtaorganellar ion imaging have led to molecular identification and functional characterization of about two dozen endomembrane ion channels. For example, whereas IP3R1-3 channels mediate Ca2+ release from the ER in response to neurotransmitter and hormone stimulation, TRPML1-3 and TMEM175 channels mediate lysosomal Ca2+ and H+ release, respectively, in response to nutritional and trafficking cues. This review aims to summarize the current understanding of these endomembrane channels, with a focus on their subcellular localizations, ion permeation properties, gating mechanisms, cell biological functions, and disease relevance.
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Affiliation(s)
- Meiqin Hu
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Xinghua Feng
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Qiang Liu
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Siyu Liu
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Fangqian Huang
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Haoxing Xu
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States
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2
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Zhou D, Eraslan Z, Miller D, Taylor I, You J, Grondin SJ, Vega M, Manga P, Goff PS, Sviderskaya EV, Gross SS, Chen Q, Zippin JH. Two-pore channel 2 is required for soluble adenylyl cyclase-dependent regulation of melanosomal pH and melanin synthesis. Pigment Cell Melanoma Res 2024. [PMID: 38844435 DOI: 10.1111/pcmr.13177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 04/25/2024] [Accepted: 05/24/2024] [Indexed: 07/17/2024]
Abstract
Melanosomal pH is important for the synthesis of melanin as the rate-limiting enzyme, tyrosinase, is very pH-sensitive. The soluble adenylyl cyclase (sAC) signaling pathway was recently identified as a regulator of melanosomal pH in melanocytes; however, the melanosomal proteins critical for sAC-dependent regulation of melanosomal pH were undefined. We now systematically examine four well-characterized melanosomal membrane proteins to determine whether any of them are required for sAC-dependent regulation of melanosomal pH. We find that OA1, OCA2, and SLC45A2 are dispensable for sAC-dependent regulation of melanosomal pH. In contrast, TPC2 activity is required for sAC-dependent regulation of melanosomal pH and melanin synthesis. In addition, activation of TPC2 by NAADP-AM rescues melanosomal pH alkalinization and reduces melanin synthesis following pharmacologic or genetic inhibition of sAC signaling. These studies establish TPC2 as a critical melanosomal protein for sAC-dependent regulation of melanosomal pH and pigmentation.
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Affiliation(s)
- Dalee Zhou
- Department of Dermatology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Zuhal Eraslan
- Department of Dermatology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Dawson Miller
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Isobel Taylor
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Jaewon You
- Department of Dermatology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Samuel J Grondin
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Martha Vega
- The Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, New York, USA
| | - Prashiela Manga
- The Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, New York, USA
| | - Philip S Goff
- Cell Biology Research Section, Molecular and Clinical Sciences Research Institute, St George's University of London, London, UK
| | - Elena V Sviderskaya
- Cell Biology Research Section, Molecular and Clinical Sciences Research Institute, St George's University of London, London, UK
| | - Steven S Gross
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Qiuying Chen
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Jonathan H Zippin
- Department of Dermatology, Weill Cornell Medical College of Cornell University, New York, New York, USA
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
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3
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Chi G, Jaślan D, Kudrina V, Böck J, Li H, Pike ACW, Rautenberg S, Krogsaeter E, Bohstedt T, Wang D, McKinley G, Fernandez-Cid A, Mukhopadhyay SMM, Burgess-Brown NA, Keller M, Bracher F, Grimm C, Dürr KL. Structural basis for inhibition of the lysosomal two-pore channel TPC2 by a small molecule antagonist. Structure 2024:S0969-2126(24)00182-5. [PMID: 38815576 DOI: 10.1016/j.str.2024.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 10/22/2023] [Accepted: 05/03/2024] [Indexed: 06/01/2024]
Abstract
Two pore channels are lysosomal cation channels with crucial roles in tumor angiogenesis and viral release from endosomes. Inhibition of the two-pore channel 2 (TPC2) has emerged as potential therapeutic strategy for the treatment of cancers and viral infections, including Ebola and COVID-19. Here, we demonstrate that antagonist SG-094, a synthetic analog of the Chinese alkaloid medicine tetrandrine with increased potency and reduced toxicity, induces asymmetrical structural changes leading to a single binding pocket at only one intersubunit interface within the asymmetrical dimer. Supported by functional characterization of mutants by Ca2+ imaging and patch clamp experiments, we identify key residues in S1 and S4 involved in compound binding to the voltage sensing domain II. SG-094 arrests IIS4 in a downward shifted state which prevents pore opening via the IIS4/S5 linker, hence resembling gating modifiers of canonical VGICs. These findings may guide the rational development of new therapeutics antagonizing TPC2 activity.
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Affiliation(s)
- Gamma Chi
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK.
| | - Dawid Jaślan
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Ludwig-Maximilians-Universität, Nussbaumstrasse 26, 80336 Munich, Germany
| | - Veronika Kudrina
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Ludwig-Maximilians-Universität, Nussbaumstrasse 26, 80336 Munich, Germany
| | - Julia Böck
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Ludwig-Maximilians-Universität, Nussbaumstrasse 26, 80336 Munich, Germany
| | - Huanyu Li
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK
| | - Ashley C W Pike
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK
| | - Susanne Rautenberg
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität, Butenandtstrasse 7, 81377 Munich, Germany
| | - Einar Krogsaeter
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Ludwig-Maximilians-Universität, Nussbaumstrasse 26, 80336 Munich, Germany
| | - Tina Bohstedt
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK
| | - Dong Wang
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK
| | - Gavin McKinley
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK
| | - Alejandra Fernandez-Cid
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK
| | - Shubhashish M M Mukhopadhyay
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK
| | - Nicola A Burgess-Brown
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK
| | - Marco Keller
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität, Butenandtstrasse 7, 81377 Munich, Germany
| | - Franz Bracher
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität, Butenandtstrasse 7, 81377 Munich, Germany
| | - Christian Grimm
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Ludwig-Maximilians-Universität, Nussbaumstrasse 26, 80336 Munich, Germany; Immunology, Infection and Pandemic Research IIP, Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Munich/Frankfurt, Germany
| | - Katharina L Dürr
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK; Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Nuffield Department of Medicine Research Building, Oxford OX3 7FZ, UK
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4
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Ouologuem L, Bartel K. Endolysosomal transient receptor potential mucolipins and two-pore channels: implications for cancer immunity. Front Immunol 2024; 15:1389194. [PMID: 38840905 PMCID: PMC11150529 DOI: 10.3389/fimmu.2024.1389194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 05/09/2024] [Indexed: 06/07/2024] Open
Abstract
Past research has identified that cancer cells sustain several cancer hallmarks by impairing function of the endolysosomal system (ES). Thus, maintaining the functional integrity of endolysosomes is crucial, which heavily relies on two key protein families: soluble hydrolases and endolysosomal membrane proteins. Particularly members of the TPC (two-pore channel) and TRPML (transient receptor potential mucolipins) families have emerged as essential regulators of ES function as a potential target in cancer therapy. Targeting TPCs and TRPMLs has demonstrated significant impact on multiple cancer hallmarks, including proliferation, growth, migration, and angiogenesis both in vitro and in vivo. Notably, endosomes and lysosomes also actively participate in various immune regulatory mechanisms, such as phagocytosis, antigen presentation, and the release of proinflammatory mediators. Yet, knowledge about the role of TPCs and TRPMLs in immunity is scarce. This prompts a discussion regarding the potential role of endolysosomal ion channels in aiding cancers to evade immune surveillance and destruction. Specifically, understanding the interplay between endolysosomal ion channels and cancer immunity becomes crucial. Our review aims to comprehensively explore the current knowledge surrounding the roles of TPCs and TRPMLs in immunity, whilst emphasizing the critical need to elucidate their specific contributions to cancer immunity by pointing out current research gaps that should be addressed.
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Affiliation(s)
| | - Karin Bartel
- Department of Pharmacy, Drug Delivery, Ludwig-Maximilians-University Munich, Munich, Germany
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5
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Humer C, Schindl R, Sallinger M. Crosstalk between TPC2 and IP 3R regulates Ca 2+ signals. Trends Cell Biol 2024; 34:352-354. [PMID: 38494377 DOI: 10.1016/j.tcb.2024.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 02/29/2024] [Accepted: 03/01/2024] [Indexed: 03/19/2024]
Abstract
Calcium (Ca2+) plays a pivotal role in cellular signal transmission by triggering downstream signaling in response to an increase in the cytosolic Ca2+ concentration. Intracellular organelles serve as Ca2+ stores that induce differently shaped Ca2+ signals. We discuss a study by Yuan et al. that investigated the interplay between the lysosomal two-pore channel 2 (TPC2) and endoplasmic reticulum (ER)-localized inositol 1,4,5-trisphosphate receptors (IP3Rs).
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Affiliation(s)
- Christina Humer
- Institute of Biophysics, Johannes Kepler University Linz, Linz, Austria
| | - Rainer Schindl
- Department of Medical Physics and Biophysics, Medical University of Graz, Graz, Austria.
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6
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Yuan Y, Jaślan D, Rahman T, Bracher F, Grimm C, Patel S. Coordinating activation of endo-lysosomal two-pore channels and TRP mucolipins. J Physiol 2024; 602:1623-1636. [PMID: 38598430 DOI: 10.1113/jp283829] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 02/12/2024] [Indexed: 04/12/2024] Open
Abstract
Two-pore channels and TRP mucolipins are ubiquitous endo-lysosomal cation channels of pathophysiological relevance. Both are Ca2+-permeable and regulated by phosphoinositides, principally PI(3,5)P2. Accumulating evidence has uncovered synergistic channel activation by PI(3,5)P2 and endogenous metabolites such as the Ca2+ mobilizing messenger NAADP, synthetic agonists including approved drugs and physical cues such as voltage and osmotic pressure. Here, we provide an overview of this coordination.
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Affiliation(s)
- Yu Yuan
- Department of Cell and Developmental Biology, UCL, London, UK
| | - Dawid Jaślan
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilian University, Munich, Germany
| | - Taufiq Rahman
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Franz Bracher
- Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians University, Munich, Germany
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilian University, Munich, Germany
- Immunology, Infection and Pandemic Research IIP, Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Frankfurt, Germany
| | - Sandip Patel
- Department of Cell and Developmental Biology, UCL, London, UK
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7
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Barbonari S, D'Amore A, Hanbashi AA, Palombi F, Riccioli A, Parrington J, Filippini A. Endolysosomal two-pore channel 2 plays opposing roles in primary and metastatic malignant melanoma cells. Cell Biol Int 2024; 48:521-540. [PMID: 38263578 DOI: 10.1002/cbin.12129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 11/10/2023] [Accepted: 01/01/2024] [Indexed: 01/25/2024]
Abstract
The ion channel two-pore channel 2 (TPC2), localised on the membranes of acidic organelles such as endo-lysosomes and melanosomes, has been shown to play a role in pathologies including cancer, and it is differently expressed in primary versus metastatic melanoma cells. Whether TPC2 plays a pro- or anti-oncogenic role in different tumour conditions is a relevant open question which we have explored in melanoma at different stages of tumour progression. The behaviour of primary melanoma cell line B16F0 and its metastatic subline B16F10 were compared in response to TPC2 modulation by silencing (by small interfering RNA), knock-out (by CRISPR/Cas9) and overexpression (by mCherry-TPC2 transfected plasmid). TPC2 silencing increased cell migration, epithelial-to-mesenchymal transition and autophagy in the metastatic samples, but abated them in the silenced primary ones. Interestingly, while TPC2 inactivation failed to affect markers of proliferation in both samples, it strongly enhanced the migratory behaviour of the metastatic cells, again suggesting that in the more aggressive phenotype TPC2 plays a specific antimetastatic role. In line with this, overexpression of TPC2 in B16F10 cells resulted in phenotype rescue, that is, a decrease in migratory ability, thus collectively resuming traits of the B16F0 primary cell line. Our research shows a novel role of TPC2 in melanoma cells that is intriguingly different in initial versus late stages of cancer progression.
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Affiliation(s)
- Samantha Barbonari
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Unit of Histology and Medical Embryology, Sapienza University, Rome, Italy
| | | | - Ali A Hanbashi
- Department of Pharmacology, University of Oxford, Oxford, UK
- Department of Pharmacology, College of Pharmacy, Jazan University, Jazan, Saudi Arabia
| | - Fioretta Palombi
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Unit of Histology and Medical Embryology, Sapienza University, Rome, Italy
| | - Anna Riccioli
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Unit of Histology and Medical Embryology, Sapienza University, Rome, Italy
| | - John Parrington
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Antonio Filippini
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Unit of Histology and Medical Embryology, Sapienza University, Rome, Italy
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8
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Yuan Y, Arige V, Saito R, Mu Q, Brailoiu GC, Pereira GJS, Bolsover SR, Keller M, Bracher F, Grimm C, Brailoiu E, Marchant JS, Yule DI, Patel S. Two-pore channel-2 and inositol trisphosphate receptors coordinate Ca 2+ signals between lysosomes and the endoplasmic reticulum. Cell Rep 2024; 43:113628. [PMID: 38160394 PMCID: PMC10931537 DOI: 10.1016/j.celrep.2023.113628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 11/13/2023] [Accepted: 12/11/2023] [Indexed: 01/03/2024] Open
Abstract
Lysosomes and the endoplasmic reticulum (ER) are Ca2+ stores mobilized by the second messengers NAADP and IP3, respectively. Here, we establish Ca2+ signals between the two sources as fundamental building blocks that couple local release to global changes in Ca2+. Cell-wide Ca2+ signals evoked by activation of endogenous NAADP-sensitive channels on lysosomes comprise both local and global components and exhibit a major dependence on ER Ca2+ despite their lysosomal origin. Knockout of ER IP3 receptor channels delays these signals, whereas expression of lysosomal TPC2 channels accelerates them. High-resolution Ca2+ imaging reveals elementary events upon TPC2 opening and signals coupled to IP3 receptors. Biasing TPC2 activation to a Ca2+-permeable state sensitizes local Ca2+ signals to IP3. This increases the potency of a physiological agonist to evoke global Ca2+ signals and activate a downstream target. Our data provide a conceptual framework to understand how Ca2+ release from physically separated stores is coordinated.
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Affiliation(s)
- Yu Yuan
- Department of Cell and Developmental Biology, University College London, Gower Street, WC1E 6BT London, UK
| | - Vikas Arige
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Ryo Saito
- Department of Cell and Developmental Biology, University College London, Gower Street, WC1E 6BT London, UK; Department of Dermatology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Qianru Mu
- Department of Cell and Developmental Biology, University College London, Gower Street, WC1E 6BT London, UK
| | - Gabriela C Brailoiu
- Department of Pharmaceutical Sciences, Jefferson College of Pharmacy, Thomas Jefferson University, 901 Walnut Street, Philadelphia, PA 19107, USA
| | - Gustavo J S Pereira
- Department of Cell and Developmental Biology, University College London, Gower Street, WC1E 6BT London, UK; Department of Pharmacology, Federal University of São Paulo (UNIFESP), São Paulo 04044-020, Brazil
| | - Stephen R Bolsover
- Department of Cell and Developmental Biology, University College London, Gower Street, WC1E 6BT London, UK
| | - Marco Keller
- Department of Pharmacy-Center for Drug Research, Ludwig-Maximilian University, Butenandtstrasse 5-13, 81377 Munich, Germany
| | - Franz Bracher
- Department of Pharmacy-Center for Drug Research, Ludwig-Maximilian University, Butenandtstrasse 5-13, 81377 Munich, Germany
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilian University, Nussbaumstrasse 26, 80336 Munich, Germany; Immunology, Infection and Pandemic Research IIP, Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, 60596 Frankfurt, Germany
| | - Eugen Brailoiu
- Department of Neural Sciences and Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Jonathan S Marchant
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - David I Yule
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA.
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, Gower Street, WC1E 6BT London, UK.
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9
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Nagy N, Pal M, Kun J, Galik B, Urban P, Medvecz M, Fabos B, Neller A, Abdolreza A, Danis J, Szabo V, Yang Z, Fenske S, Biel M, Gyenesei A, Adam E, Szell M. Missing Heritability in Albinism: Deep Characterization of a Hungarian Albinism Cohort Raises the Possibility of the Digenic Genetic Background of the Disease. Int J Mol Sci 2024; 25:1271. [PMID: 38279271 PMCID: PMC10817051 DOI: 10.3390/ijms25021271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 01/28/2024] Open
Abstract
Albinism is characterized by a variable degree of hypopigmentation affecting the skin and the hair, and causing ophthalmologic abnormalities. Its oculocutaneous, ocular and syndromic forms follow an autosomal or X-linked recessive mode of inheritance, and 22 disease-causing genes are implicated in their development. Our aim was to clarify the genetic background of a Hungarian albinism cohort. Using a 22-gene albinism panel, the genetic background of 11 of the 17 Hungarian patients was elucidated. In patients with unidentified genetic backgrounds (n = 6), whole exome sequencing was performed. Our investigations revealed a novel, previously unreported rare variant (N687S) of the two-pore channel two gene (TPCN2). The N687S variant of the encoded TPC2 protein is carried by a 15-year-old Hungarian male albinism patient and his clinically unaffected mother. Our segregational analysis and in vitro functional experiments suggest that the detected novel rare TPCN2 variant alone is not a disease-causing variant in albinism. Deep genetic analyses of the family revealed that the patient also carries a phenotype-modifying R305W variant of the OCA2 protein, and he is the only family member harboring this genotype. Our results raise the possibility that this digenic combination might contribute to the observed differences between the patient and the mother, and found the genetic background of the disease in his case.
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Affiliation(s)
- Nikoletta Nagy
- Department of Medical Genetics, University of Szeged, 6720 Szeged, Hungary; (M.P.); (A.N.); (A.A.); (E.A.); (M.S.)
- HUN-REN-SZTE Functional Clinical Genetic Research Group, 6720 Szeged, Hungary
| | - Margit Pal
- Department of Medical Genetics, University of Szeged, 6720 Szeged, Hungary; (M.P.); (A.N.); (A.A.); (E.A.); (M.S.)
- HUN-REN-SZTE Functional Clinical Genetic Research Group, 6720 Szeged, Hungary
| | - Jozsef Kun
- Hungarian Centre for Genomics and Bioinformatics, Szentagothai Research Centre, University of Pecs, 7624 Pecs, Hungary; (J.K.); (B.G.); (P.U.); (A.G.)
| | - Bence Galik
- Hungarian Centre for Genomics and Bioinformatics, Szentagothai Research Centre, University of Pecs, 7624 Pecs, Hungary; (J.K.); (B.G.); (P.U.); (A.G.)
| | - Peter Urban
- Hungarian Centre for Genomics and Bioinformatics, Szentagothai Research Centre, University of Pecs, 7624 Pecs, Hungary; (J.K.); (B.G.); (P.U.); (A.G.)
| | - Marta Medvecz
- Department of Dermatology, Venereology and Dermatooncology, Semmelweis University, 1095 Budapest, Hungary;
- ERN-Skin Reference Centre, Semmelweis University, 1095 Budapest, Hungary
| | - Beata Fabos
- Mor Kaposi Teaching Hospital of Somogy County, 7400 Kaposvar, Hungary;
| | - Alexandra Neller
- Department of Medical Genetics, University of Szeged, 6720 Szeged, Hungary; (M.P.); (A.N.); (A.A.); (E.A.); (M.S.)
| | - Aliasgari Abdolreza
- Department of Medical Genetics, University of Szeged, 6720 Szeged, Hungary; (M.P.); (A.N.); (A.A.); (E.A.); (M.S.)
| | - Judit Danis
- HUN-REN-SZTE Dermatological Research Group, 6720 Szeged, Hungary;
- Department of Immunology, University of Szeged, 6720 Szeged, Hungary
| | - Viktoria Szabo
- Department of Ophthalmology, Semmelweis University, 1085 Budapest, Hungary
| | - Zhuo Yang
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany (M.B.)
| | - Stefanie Fenske
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany (M.B.)
| | - Martin Biel
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany (M.B.)
| | - Attila Gyenesei
- Hungarian Centre for Genomics and Bioinformatics, Szentagothai Research Centre, University of Pecs, 7624 Pecs, Hungary; (J.K.); (B.G.); (P.U.); (A.G.)
| | - Eva Adam
- Department of Medical Genetics, University of Szeged, 6720 Szeged, Hungary; (M.P.); (A.N.); (A.A.); (E.A.); (M.S.)
- HUN-REN-SZTE Functional Clinical Genetic Research Group, 6720 Szeged, Hungary
| | - Marta Szell
- Department of Medical Genetics, University of Szeged, 6720 Szeged, Hungary; (M.P.); (A.N.); (A.A.); (E.A.); (M.S.)
- HUN-REN-SZTE Functional Clinical Genetic Research Group, 6720 Szeged, Hungary
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10
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Davis LC, Morgan AJ, Galione A. Optical profiling of autonomous Ca 2+ nanodomains generated by lysosomal TPC2 and TRPML1. Cell Calcium 2023; 116:102801. [PMID: 37742482 DOI: 10.1016/j.ceca.2023.102801] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 08/30/2023] [Accepted: 09/17/2023] [Indexed: 09/26/2023]
Abstract
Multiple families of Ca2+-permeable channels co-exist on lysosomal Ca2+ stores but how each family couples to its own unique downstream physiology is unclear. We have therefore investigated the Ca2+-signalling architecture underpinning different channels on the same vesicle that drive separate pathways, using phagocytosis as a physiological stimulus. Lysosomal Ca2+-channels are a major Ca2+ source driving particle uptake in macrophages, but different channels drive different aspects of Fc-receptor-mediated phagocytosis: TPC2 couples to dynamin activation, whilst TRPML1 couples to lysosomal exocytosis. We hypothesised that they are driven by discrete local plumes of Ca2+ around open channels (Ca2+ nanodomains). To test this, we optimized Ca2+-nanodomain recordings by screening panels of genetically encoded Ca2+ indicators (GECIs) fused to TPC2 to monitor the [Ca2+] next to the channel. Signal calibration accounting for the distance of the GECI from the channel mouth reveals that, during phagocytosis, TPC2 generates local Ca2+ nanodomains around itself of up to 42 µM, nearly a hundred-fold greater than the global cytosolic [Ca2+] rise. We further show that TPC2 and TRPML1, though on the same lysosomes, generate autonomous Ca2+ nanodomains of high [Ca2+] that are largely insulated from one another, a platform allowing their discrete Ca2+-decoding to promote unique respective physiologies.
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Affiliation(s)
- Lianne C Davis
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Anthony J Morgan
- 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.
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11
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Moccia F, Morgan AJ. TPC2 gating: Trying to break the enigma code. Cell Calcium 2023; 116:102815. [PMID: 38980391 DOI: 10.1016/j.ceca.2023.102815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 10/17/2023] [Accepted: 10/17/2023] [Indexed: 07/10/2024]
Affiliation(s)
- Francesco Moccia
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia 27100, Italy.
| | - Anthony J Morgan
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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12
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Potokar M, Zorec R, Jorgačevski J. Astrocytes Are a Key Target for Neurotropic Viral Infection. Cells 2023; 12:2307. [PMID: 37759529 PMCID: PMC10528686 DOI: 10.3390/cells12182307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 08/28/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023] Open
Abstract
Astrocytes are increasingly recognized as important viral host cells in the central nervous system. These cells can produce relatively high quantities of new virions. In part, this can be attributed to the characteristics of astrocyte metabolism and its abundant and dynamic cytoskeleton network. Astrocytes are anatomically localized adjacent to interfaces between blood capillaries and brain parenchyma and between blood capillaries and brain ventricles. Moreover, astrocytes exhibit a larger membrane interface with the extracellular space than neurons. These properties, together with the expression of various and numerous viral entry receptors, a relatively high rate of endocytosis, and morphological plasticity of intracellular organelles, render astrocytes important target cells in neurotropic infections. In this review, we describe factors that mediate the high susceptibility of astrocytes to viral infection and replication, including the anatomic localization of astrocytes, morphology, expression of viral entry receptors, and various forms of autophagy.
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Affiliation(s)
- Maja Potokar
- Laboratory of Neuroendocrinology–Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
- Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology–Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
- Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia
| | - Jernej Jorgačevski
- Laboratory of Neuroendocrinology–Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
- Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia
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13
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Saito R, Mu Q, Yuan Y, Rubio-Alarcón M, Eznarriaga M, Zhao P, Gunaratne G, Kumar S, Keller M, Bracher F, Grimm C, Brailoiu E, Marchant JS, Rahman T, Patel S. Convergent activation of Ca 2+ permeability in two-pore channel 2 through distinct molecular routes. Sci Signal 2023; 16:eadg0661. [PMID: 37607219 PMCID: PMC10639088 DOI: 10.1126/scisignal.adg0661] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 07/27/2023] [Indexed: 08/24/2023]
Abstract
TPC2 is a pathophysiologically relevant lysosomal ion channel that is activated directly by the phosphoinositide PI(3,5)P2 and indirectly by the calcium ion (Ca2+)-mobilizing molecule NAADP through accessory proteins that associate with the channel. TPC2 toggles between PI(3,5)P2-induced, sodium ion (Na+)-selective and NAADP-induced, Ca2+-permeable states in response to these cues. To address the molecular basis of polymodal gating and ion-selectivity switching, we investigated the mechanism by which NAADP and its synthetic functional agonist, TPC2-A1-N, induced Ca2+ release through TPC2 in human cells. Whereas NAADP required the NAADP-binding proteins JPT2 and LSM12 to evoke endogenous calcium ion signals, TPC2-A1-N did not. Residues in TPC2 that bind to PI(3,5)P2 were required for channel activation by NAADP but not for activation by TPC2-A1-N. The cryptic voltage-sensing region of TPC2 was required for the actions of TPC2-A1-N and PI(3,5)P2 but not for those of NAADP. These data mechanistically distinguish natural and synthetic agonist action at TPC2 despite convergent effects on Ca2+ permeability and delineate a route for pharmacologically correcting impaired NAADP-evoked Ca2+ signals.
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Affiliation(s)
- Ryo Saito
- Department of Cell and Developmental Biology, University
College London, Gower Street, London WC1E 6BT, UK
- Department of Dermatology, Graduate School of Biomedical
and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Qianru Mu
- Department of Cell and Developmental Biology, University
College London, Gower Street, London WC1E 6BT, UK
| | - Yu Yuan
- Department of Cell and Developmental Biology, University
College London, Gower Street, London WC1E 6BT, UK
| | | | - Maria Eznarriaga
- Department of Pharmacology, University of Cambridge,
Cambridge, UK
| | - Pingwei Zhao
- Center for Substance Abuse Research, Lewis Katz School of
Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Gihan Gunaratne
- Department of Cell Biology, Neurobiology and Anatomy,
Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226,
USA
| | - Sushil Kumar
- Department of Cell Biology, Neurobiology and Anatomy,
Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226,
USA
| | - Marco Keller
- Department of Pharmacy—Center for Drug Research,
Ludwig-Maximilian University, Munich, Germany
| | - Franz Bracher
- Department of Pharmacy—Center for Drug Research,
Ludwig-Maximilian University, Munich, Germany
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology,
Faculty of Medicine, Ludwig-Maximilians University, Munich, Germany
| | - Eugen Brailoiu
- Center for Substance Abuse Research, Lewis Katz School of
Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Jonathan S. Marchant
- Department of Cell Biology, Neurobiology and Anatomy,
Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226,
USA
| | - Taufiq Rahman
- Department of Pharmacology, University of Cambridge,
Cambridge, UK
| | - Sandip Patel
- Department of Cell and Developmental Biology, University
College London, Gower Street, London WC1E 6BT, UK
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14
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Zhu J, Yan H, Shi M, Zhang M, Lu J, Wang J, Chen L, Wang Y, Li L, Miao L, Zhang H. Luteolin inhibits spike protein of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) binding to angiotensin-converting enzyme 2. Phytother Res 2023; 37:3508-3521. [PMID: 37166054 DOI: 10.1002/ptr.7826] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 03/16/2023] [Accepted: 03/24/2023] [Indexed: 05/12/2023]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), a respiratory illness that poses a serious threat to global public health. In an essential step during infection, SARS-CoV-2 uses the receptor-binding domain (RBD) of the spike (S) protein to engage with angiotensin-converting enzyme 2 (ACE2) in host cells. Chinese herbal medicines and their active components exhibit antiviral activity, with luteolin being a flavonoid that can significantly inhibit SARS-CoV infection. However, whether it can block the interaction between the S-protein RBD of SARS-CoV-2 and ACE2 has not yet been elucidated. Here, we investigated the effects of luteolin on the binding of the S-protein RBD to ACE2. By employing a competitive binding assay in vitro, we found that luteolin significantly blocked the binding of S-protein RBD to ACE2 with IC50 values of 0.61 mM, which was confirmed by the neutralized infection with SARS-CoV-2 pseudovirus in vivo. A surface plasmon resonance-based competition assay revealed that luteolin significantly affects the binding of the S-protein RBD to the ACE2 receptor. Molecular docking was performed to predict the binding sites of luteolin to the S-protein RBD-ACE2 complex. The active binding sites were defined based on published literature, and we found that luteolin might interfere with the mixture at residues including LYS353, ASP30, and TYR83 in the cellular ACE2 receptor and GLY496, GLN498, TYR505, LEU455, GLN493, and GLU484 in the S-protein RBD. These residues may together form attractive charges and destroy the stable interaction of S-protein RBD-ACE2. Luteolin also inhibits SARS-CoV-2 spike protein-induced platelet spreading, thereby inhibiting the binding of the spike protein to ACE2. Our results are the first to provide evidence that luteolin is an anti-SARS-CoV-2 agent associated with interference between viral S-protein RBD-ACE2 interactions.
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Affiliation(s)
- Junjie Zhu
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Huimin Yan
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Mengyao Shi
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Key Laboratory of Pharmacology of Traditional Chinese Medical Formulae, Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Min Zhang
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Key Laboratory of Pharmacology of Traditional Chinese Medical Formulae, Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Jia Lu
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Key Laboratory of Pharmacology of Traditional Chinese Medical Formulae, Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Jiabao Wang
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Key Laboratory of Pharmacology of Traditional Chinese Medical Formulae, Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Lu Chen
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Key Laboratory of Pharmacology of Traditional Chinese Medical Formulae, Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Yu Wang
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Key Laboratory of Pharmacology of Traditional Chinese Medical Formulae, Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Lin Li
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Key Laboratory of Pharmacology of Traditional Chinese Medical Formulae, Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Lin Miao
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Key Laboratory of Pharmacology of Traditional Chinese Medical Formulae, Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Han Zhang
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Key Laboratory of Pharmacology of Traditional Chinese Medical Formulae, Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin, China
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15
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Hedrich R, Müller TD, Marten I, Becker D. TPC1 vacuole SV channel gains further shape - voltage priming of calcium-dependent gating. TRENDS IN PLANT SCIENCE 2023; 28:673-684. [PMID: 36740491 DOI: 10.1016/j.tplants.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/20/2022] [Accepted: 01/11/2023] [Indexed: 05/13/2023]
Abstract
Across phyla, voltage-gated ion channels (VGICs) allow excitability. The vacuolar two-pore channel AtTPC1 from the tiny mustard plant Arabidopsis thaliana has emerged as a paradigm for deciphering the role of voltage and calcium signals in membrane excitation. Among the numerous experimentally determined structures of VGICs, AtTPC1 was the first to be revealed in a closed and resting state, fueling speculation about structural rearrangements during channel activation. Two independent reports on the structure of a partially opened AtTPC1 channel protein have led to working models that offer promising insights into the molecular switches associated with the gating process. We review new structure-function models and also discuss the evolutionary impact of two-pore channels (TPCs) on K+ homeostasis and vacuolar excitability.
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Affiliation(s)
- Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany.
| | - Thomas D Müller
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Irene Marten
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Dirk Becker
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
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16
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Wang H, Zhu Y, Liu H, Liang T, Wei Y. Advances in Drug Discovery Targeting Lysosomal Membrane Proteins. Pharmaceuticals (Basel) 2023; 16:ph16040601. [PMID: 37111358 PMCID: PMC10145713 DOI: 10.3390/ph16040601] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/10/2023] [Accepted: 03/14/2023] [Indexed: 04/29/2023] Open
Abstract
Lysosomes are essential organelles of eukaryotic cells and are responsible for various cellular functions, including endocytic degradation, extracellular secretion, and signal transduction. There are dozens of proteins localized to the lysosomal membrane that control the transport of ions and substances across the membrane and are integral to lysosomal function. Mutations or aberrant expression of these proteins trigger a variety of disorders, making them attractive targets for drug development for lysosomal disorder-related diseases. However, breakthroughs in R&D still await a deeper understanding of the underlying mechanisms and processes of how abnormalities in these membrane proteins induce related diseases. In this article, we summarize the current progress, challenges, and prospects for developing therapeutics targeting lysosomal membrane proteins for the treatment of lysosomal-associated diseases.
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Affiliation(s)
- Hongna Wang
- Affiliated Cancer Hospital, Institute of Guangzhou Medical University, Guangzhou 510095, China
- Key Laboratory for Cell Homeostasis, Cancer Research of Guangdong Higher Education Institutes, Guangzhou 510095, China
| | - Yidong Zhu
- Affiliated Cancer Hospital, Institute of Guangzhou Medical University, Guangzhou 510095, China
- Key Laboratory for Cell Homeostasis, Cancer Research of Guangdong Higher Education Institutes, Guangzhou 510095, China
| | - Huiyan Liu
- Affiliated Cancer Hospital, Institute of Guangzhou Medical University, Guangzhou 510095, China
- Key Laboratory for Cell Homeostasis, Cancer Research of Guangdong Higher Education Institutes, Guangzhou 510095, China
| | - Tianxiang Liang
- Affiliated Cancer Hospital, Institute of Guangzhou Medical University, Guangzhou 510095, China
- Key Laboratory for Cell Homeostasis, Cancer Research of Guangdong Higher Education Institutes, Guangzhou 510095, China
| | - Yongjie Wei
- Affiliated Cancer Hospital, Institute of Guangzhou Medical University, Guangzhou 510095, China
- Key Laboratory for Cell Homeostasis, Cancer Research of Guangdong Higher Education Institutes, Guangzhou 510095, China
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Guangzhou 510095, China
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17
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Wahl-Schott C, Freichel M, Hennis K, Philippaert K, Ottenheijm R, Tsvilovskyy V, Varbanov H. Characterization of Endo-Lysosomal Cation Channels Using Calcium Imaging. Handb Exp Pharmacol 2023; 278:277-304. [PMID: 36894791 DOI: 10.1007/164_2023_637] [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: 03/11/2023]
Abstract
Endo-lysosomes are membrane-bound acidic organelles that are involved in endocytosis, recycling, and degradation of extracellular and intracellular material. The membranes of endo-lysosomes express several Ca2+-permeable cation ion channels, including two-pore channels (TPC1-3) and transient receptor potential mucolipin channels (TRPML1-3). In this chapter, we will describe four different state-of-the-art Ca2+ imaging approaches, which are well-suited to investigate the function of endo-lysosomal cation channels. These techniques include (1) global cytosolic Ca2+ measurements, (2) peri-endo-lysosomal Ca2+ imaging using genetically encoded Ca2+ sensors that are directed to the cytosolic endo-lysosomal membrane surface, (3) Ca2+ imaging of endo-lysosomal cation channels, which are engineered in order to redirect them to the plasma membrane in combination with approaches 1 and 2, and (4) Ca2+ imaging by directing Ca2+ indicators to the endo-lysosomal lumen. Moreover, we will review useful small molecules, which can be used as valuable tools for endo-lysosomal Ca2+ imaging. Rather than providing complete protocols, we will discuss specific methodological issues related to endo-lysosomal Ca2+ imaging.
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Affiliation(s)
- Christian Wahl-Schott
- Institut für Kardiovaskuläre Physiologie und Pathophysiologie, Lehrstuhl für Vegetative Physiologie, Biomedizinisches Zentrum, Ludwig-Maximilians-Universität München, München, Germany.
| | - Marc Freichel
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany. .,DZHK (German Centre for Cardiovascular Research), Heidelberg/Mannheim, Germany.
| | - Konstantin Hennis
- Institut für Kardiovaskuläre Physiologie und Pathophysiologie, Lehrstuhl für Vegetative Physiologie, Biomedizinisches Zentrum, Ludwig-Maximilians-Universität München, München, Germany
| | - Koenraad Philippaert
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Heidelberg/Mannheim, Germany
| | - Roger Ottenheijm
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Heidelberg/Mannheim, Germany
| | - Volodymyr Tsvilovskyy
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Heidelberg/Mannheim, Germany
| | - Hristo Varbanov
- Institut für Neurophysiologie, Medizinische Hochschule Hannover(MHH), Hannover, Germany
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18
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Riederer E, Cang C, Ren D. Lysosomal Ion Channels: What Are They Good For and Are They Druggable Targets? Annu Rev Pharmacol Toxicol 2023; 63:19-41. [PMID: 36151054 DOI: 10.1146/annurev-pharmtox-051921-013755] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Lysosomes play fundamental roles in material digestion, cellular clearance, recycling, exocytosis, wound repair, Ca2+ signaling, nutrient signaling, and gene expression regulation. The organelle also serves as a hub for important signaling networks involving the mTOR and AKT kinases. Electrophysiological recording and molecular and structural studies in the past decade have uncovered several unique lysosomal ion channels and transporters, including TPCs, TMEM175, TRPMLs, CLN7, and CLC-7. They underlie the organelle's permeability to major ions, including K+, Na+, H+, Ca2+, and Cl-. The channels are regulated by numerous cellular factors, ranging from H+ in the lumen and voltage across the lysosomal membrane to ATP in the cytosol to growth factors outside the cell. Genetic variations in the channel/transporter genes are associated with diseases that include lysosomal storage diseases and neurodegenerative diseases. Recent studies with human genetics and channel activators suggest that lysosomal channels may be attractive targets for the development of therapeutics for the prevention of and intervention in human diseases.
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Affiliation(s)
- Erika Riederer
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA; ,
| | - Chunlei Cang
- CAS Key Laboratory of Innate Immunity and Chronic Disease, Neurodegenerative Disorder Research Center, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China;
| | - Dejian Ren
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA; ,
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19
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A gain-of-function TPC2 variant R210C increases affinity to PI(3,5)P 2 and causes lysosome acidification and hypopigmentation. Nat Commun 2023; 14:226. [PMID: 36641477 PMCID: PMC9840614 DOI: 10.1038/s41467-023-35786-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 12/29/2022] [Indexed: 01/15/2023] Open
Abstract
Albinism is a group of inherited disorders mainly affecting skin, hair and eyes. Here we identify a de novo point mutation, p.R210C, in the TPCN2 gene which encodes Two Pore Channel 2 (TPC2) from a patient with albinism. TPC2 is an endolysosome and melanosome localized non-selective cation channel involved in regulating pigment production. Through inside-out recording of plasma membrane targeted TPC2 and direct recording of enlarged endolysosomal vacuoles, we reveal that the R210C mutant displays constitutive channel activation and markedly increased affinity to PI(3,5)P2. Mice harboring the homologous mutation, R194C, also exhibit hypopigmentation in the fur and skin, as well as less pigment and melanosomes in the retina in a dominant inheritance manner. Moreover, mouse embryonic fibroblasts carrying the R194C mutation show enlarged endolysosomes, enhanced lysosomal Ca2+ release and hyper-acidification. Our data suggest that R210C is a pathogenic gain-of-function TPC2 variant that underlies an unusual dominant type of albinism.
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20
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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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21
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She J, Guo J, Jiang Y. Structure and Function of Plant and Mammalian TPC Channels. Handb Exp Pharmacol 2023; 278:155-180. [PMID: 35879575 DOI: 10.1007/164_2022_599] [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) belong to the family of voltage-gated tetrameric cation channels and are ubiquitously expressed in organelles of animals and plants. These channels are believed to be evolutionary intermediates between homotetrameric voltage-gated potassium/sodium channels and the four-domain, single subunit, voltage-gated sodium/calcium channels. Each TPC subunit contains 12 transmembrane segments that can be divided into two homologous copies of an S1-S6 Shaker-like 6-TM domain. A functional TPC channel assembles as a dimer - the equivalent of a voltage-gated tetrameric cation channel. The plant TPC channel is localized in the vacuolar membrane and is also called the SV channel for generating the slow vacuolar (SV) current observed long before its molecular identification. Three subfamilies of mammalian TPC channels have been defined - TPC1, 2, and 3 - with the first two being ubiquitously expressed in animals and TPC3 being expressed in some animals but not in humans. Mammalian TPC1 and TPC2 are localized to the endolysosomal membrane and their functions are associated with various physiological processes. TPC3 is localized in the plasma membrane and its physiological function is not well defined.
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Affiliation(s)
- Ji She
- MOE Key Laboratory for Cellular Dynamics, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Jiangtao Guo
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Department of Neurology, the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Youxing Jiang
- Howard Hughes Medical Institute, Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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22
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Wang Q, Zhu MX. NAADP-Dependent TPC Current. Handb Exp Pharmacol 2023; 278:35-56. [PMID: 35902437 DOI: 10.1007/164_2022_606] [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, TPC1 and TPC2, are Ca2+- and Na+-permeable cation channels expressed on the membranes of endosomes and lysosomes in nearly all mammalian cells. These channels have been implicated in Ca2+ signaling initiated from the endolysosomes, vesicular trafficking, cellular metabolism, macropinocytosis, and viral infection. Although TPCs have been shown to mediate Ca2+ release from acidic organelles in response to NAADP (nicotinic acid adenine dinucleotide phosphate), the most potent Ca2+ mobilizing messenger, questions remain whether NAADP is a direct ligand of these channels. In whole-endolysosomal patch clamp recordings, it has been difficult to detect NAADP-evoked currents in vacuoles that expressed TPC1 or TPC2, while PI(3,5)P2 (phosphatidylinositol 3,5-bisphosphate) activated a highly Na+-selective current under the same experimental configuration. In this chapter, we summarize recent progress in this area and provide our observations on NAADP-elicited TPC2 currents from enlarged endolysosomes as well as their possible relationships with the currents evoked by PI(3,5)P2. We propose that TPCs are channels dually regulated by PI(3,5)P2 and NAADP in an interdependent manner and the two endogenous ligands may have both distinguished and cooperative roles.
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Affiliation(s)
- Qiaochu Wang
- Beijing Children's Hospital, Capital Medical University, Beijing, China
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA.
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23
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Dietrich P, Gradogna A, Carpaneto A. The Plant Vacuole as Heterologous System to Characterize the Functional Properties of TPC Channels. Handb Exp Pharmacol 2023; 278:235-247. [PMID: 35879579 DOI: 10.1007/164_2022_604] [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
Human TPC channels are an emerging family of intracellular proteins fundamental for cell physiology and involved in various severe pathologies. Their localization in the membranes of endo-lysosomes, intracellular compartments of submicrometric dimensions, makes their study difficult with usual electrophysiological techniques. In this work, we show how the plant vacuole, a versatile organelle that can occupy up to 90% of the volume in mature plant cells, can be used as a heterologous system of expression for functional characterization. For this purpose, the use of vacuoles isolated from mesophyll cells of the Arabidopsis thaliana mutant lacking the endogenous TPC avoids unwanted interferences. The patch-clamp technique can be successfully applied to plant vacuoles in all different configuration modes; of note, the whole-vacuole configuration allows to study channel modulation by cytosolic factors. The combination of patch-clamp with fluorescence techniques, for example, by using fluorescent probes sensitive to specific ions of interest, represents a useful extension to investigate the selectivity properties of the channels. Therefore, the plant vacuole, similar to Xenopus oocytes for ion channels and transporters localized in the plasma membrane, has the capability to become a model system for functional studies on intracellular ion channels and transporters.
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Affiliation(s)
- P Dietrich
- Lehrstuhl für Molekulare Pflanzenphysiologie, Department Biologie Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | | | - A Carpaneto
- Institute of Biophysics, Genoa, Italy.
- Department of Earth, Environment and Life Sciences (DISTAV) - University of Genoa, Genoa, Italy.
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24
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Patel S, Zissimopoulos S, Marchant JS. Endo-Lysosomal Two-Pore Channels and Their Protein Partners. Handb Exp Pharmacol 2023; 278:199-214. [PMID: 35902438 DOI: 10.1007/164_2022_601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Two-pore channels are ion channels expressed on acidic organelles such as the various vesicles that constitute the endo-lysosomal system. They are permeable to Ca2+ and Na+ and activated by the second messenger NAADP as well as the phosphoinositide, PI(3,5)P2 and/or voltage. Here, we review the proteins that interact with these channels including recently identified NAADP receptors.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, London, UK.
| | | | - Jonathan S Marchant
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
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25
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Minicozzi V, Qi T, Gradogna A, Pozzolini M, Milenkovic S, Filippini A, Ceccarelli M, Carpaneto A. A commentary on the inhibition of human TPC2 channel by the natural flavonoid naringenin: Methods, experiments, and ideas. Biomol Concepts 2023; 14:bmc-2022-0036. [PMID: 37677148 DOI: 10.1515/bmc-2022-0036] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 08/14/2023] [Indexed: 09/09/2023] Open
Abstract
Human endo-lysosomes possess a class of proteins called TPC channels on their membrane, which are essential for proper cell functioning. This protein family can be functionally studied by expressing them in plant vacuoles. Inhibition of hTPC activity by naringenin, one of the main flavonoids present in the human diet, has the potential to be beneficial in severe human diseases such as solid tumor development, melanoma, and viral infections. We attempted to identify the molecular basis of the interaction between hTPC2 and naringenin, using ensemble docking on molecular dynamics (MD) trajectories, but the specific binding site remains elusive, posing a challenge that could potentially be addressed in the future by increased computational power in MD and the combined use of microscopy techniques such as cryo-EM.
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Affiliation(s)
- Velia Minicozzi
- INFN and Department of Physics, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy
| | - Tianwen Qi
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Viale Benedetto XV 5, 16132 Genova, Italy
| | - Antonella Gradogna
- Institute of Biophysics, National Research Council, Via De Marini 6, 16149 Genova, Italy
| | - Marina Pozzolini
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Viale Benedetto XV 5, 16132 Genova, Italy
| | - Stefan Milenkovic
- Department of Physics, University of Cagliari, 09042 Monserrato, Italy
| | - Antonio Filippini
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University, 16 Via A. Scarpa, 00161 Rome, Italy
| | - Matteo Ceccarelli
- Department of Physics, University of Cagliari, 09042 Monserrato, Italy
| | - Armando Carpaneto
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Viale Benedetto XV 5, 16132 Genova, Italy
- Institute of Biophysics, National Research Council, Via De Marini 6, 16149 Genova, Italy
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26
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Jaślan D, Ferro IF, Kudrina V, Yuan Y, Patel S, Grimm C. PI(3,5)P 2 and NAADP: Team players or lone warriors? - New insights into TPC activation modes. Cell Calcium 2023; 109:102675. [PMID: 36525777 DOI: 10.1016/j.ceca.2022.102675] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 12/13/2022]
Abstract
NAADP (nicotinic acid adenine dinucleotide phosphate) is a second messenger, releasing Ca2+ from acidic calcium stores such as endosomes and lysosomes. PI(3,5)P2 (phosphatidylinositol 3,5-bisphosphate) is a phospho-inositide, residing on endolysosomal membranes and likewise releasing Ca2+ from endosomes and lysosomes. Both compounds have been shown to activate endolysosomal two-pore channels (TPCs) in mammalian cells. However, their effects on ion permeability as demonstrated specifically for TPC2 differ. While PI(3,5)P2 elicits predominantly Na+-selective currents, NAADP increases the Ca2+ permeability of the channel. What happens when both compounds are applied simultaneously was unclear until recently.
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Affiliation(s)
- Dawid Jaślan
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-University, Munich, Germany
| | - Irene Flavia Ferro
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-University, Munich, Germany
| | - Veronika Kudrina
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-University, Munich, Germany
| | - Yu Yuan
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, United Kingdom
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, United Kingdom
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-University, Munich, Germany.
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27
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Du C, Guan X, Yan J. Two-pore channel blockade by phosphoinositide kinase inhibitors YM201636 and PI-103 determined by a histidine residue near pore-entrance. Commun Biol 2022; 5:738. [PMID: 35871252 PMCID: PMC9308409 DOI: 10.1038/s42003-022-03701-5] [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: 02/14/2022] [Accepted: 07/11/2022] [Indexed: 12/04/2022] Open
Abstract
Human two-pore channels (TPCs) are endolysosomal cation channels and play an important role in NAADP-evoked Ca2+ release and endomembrane dynamics. We found that YM201636, a PIKfyve inhibitor, potently inhibits PI(3,5)P2-activated human TPC2 with an IC50 of 0.16 μM. YM201636 also effectively inhibits NAADP-activated TPC2 and a constitutively-open TPC2 L690A/L694A mutant channel; whereas it exerts little effect when applied in the channel’s closed state. PI-103, a YM201636 analog and an inhibitor of PI3K and mTOR, also inhibits human TPC2 with an IC50 of 0.64 μM. With mutational, virtual docking, and molecular dynamic simulation analyses, we found that YM201636 and PI-103 directly block the TPC2’s open-state channel pore at the bundle-cross pore-gate region where a nearby H699 residue is a key determinant for channel’s sensitivity to the inhibitors. H699 likely interacts with the blockers around the pore entrance and facilitates their access to the pore. Substitution of a Phe for H699 largely accounts for the TPC1 channel’s insensitivity to YM201636. These findings identify two potent TPC2 channel blockers, reveal a channel pore entrance blockade mechanism, and provide an ion channel target in interpreting the pharmacological effects of two commonly used phosphoinositide kinase inhibitors. YM201636 and PI-103 are potent inhibitors of human two-pore channel 2 that act through a channel pore entrance blockade mechanism.
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28
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Guse AH. Tuning TPC2. Cell Calcium 2022; 108:102653. [PMID: 36279843 DOI: 10.1016/j.ceca.2022.102653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 09/16/2022] [Indexed: 01/25/2023]
Affiliation(s)
- Andreas H Guse
- The Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg, 20246 Germany.
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29
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Russell T, Gangotia D, Barry G. Assessing the potential of repurposing ion channel inhibitors to treat emerging viral diseases and the role of this host factor in virus replication. Biomed Pharmacother 2022; 156:113850. [DOI: 10.1016/j.biopha.2022.113850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/25/2022] [Accepted: 10/06/2022] [Indexed: 12/03/2022] Open
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30
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You J, Yusupova M, Zippin JH. The potential impact of melanosomal pH and metabolism on melanoma. Front Oncol 2022; 12:887770. [PMID: 36483028 PMCID: PMC9723380 DOI: 10.3389/fonc.2022.887770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 08/08/2022] [Indexed: 11/23/2022] Open
Abstract
Melanin is synthesized in melanocytes and is transferred into keratinocytes to block the effects of ultraviolet (UV) radiation and is important for preventing skin cancers including melanoma. However, it is known that after melanomagenesis and melanoma invasion or metastases, melanin synthesis still occurs. Since melanoma cells are no longer involved in the sun tanning process, it is unclear why melanocytes would maintain melanin synthesis after melanomagenesis has occurred. Aside from blocking UV-induced DNA mutation, melanin may provide other metabolic functions that could benefit melanoma. In addition, studies have suggested that there may be a selective advantage to melanin synthesis in melanoma; however, mechanisms regulating melanin synthesis outside the epidermis or hair follicle is unknown. We will discuss how melanosomal pH controls melanin synthesis in melanocytes and how melanosomal pH control of melanin synthesis might function in melanoma. We will also discuss potential reasons why melanin synthesis might be beneficial for melanoma cellular metabolism and provide a rationale for why melanin synthesis is not limited to benign melanocytes.
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31
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Schmidpeter PAM, Wu D, Rheinberger J, Riegelhaupt PM, Tang H, Robinson CV, Nimigean CM. Anionic lipids unlock the gates of select ion channels in the pacemaker family. Nat Struct Mol Biol 2022; 29:1092-1100. [PMID: 36352139 PMCID: PMC10022520 DOI: 10.1038/s41594-022-00851-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 09/25/2022] [Indexed: 11/11/2022]
Abstract
Lipids play important roles in regulating membrane protein function, but the molecular mechanisms used are elusive. Here we investigated how anionic lipids modulate SthK, a bacterial pacemaker channel homolog, and HCN2, whose activity contributes to pacemaking in the heart and brain. Using SthK allowed the reconstitution of purified channels in controlled lipid compositions for functional and structural assays that are not available for the eukaryotic channels. We identified anionic lipids bound tightly to SthK and their exact binding locations and determined that they potentiate channel activity. Cryo-EM structures in the most potentiating lipids revealed an open state and identified a nonannular lipid bound with its headgroup near an intersubunit salt bridge that clamps the intracellular channel gate shut. Breaking this conserved salt bridge abolished lipid modulation in SthK and eukaryotic HCN2 channels, indicating that anionic membrane lipids facilitate channel opening by destabilizing these interactions. Our findings underline the importance of state-dependent protein-lipid interactions.
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Affiliation(s)
| | - Di Wu
- Department of Chemistry, University of Oxford, Oxford, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Jan Rheinberger
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA
- Department of Structural Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | | | - Haiping Tang
- Department of Chemistry, University of Oxford, Oxford, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, Oxford, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Crina M Nimigean
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA.
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32
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Two-pore channels: going with the flows. Biochem Soc Trans 2022; 50:1143-1155. [PMID: 35959977 PMCID: PMC9444070 DOI: 10.1042/bst20220229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/21/2022] [Accepted: 07/25/2022] [Indexed: 11/26/2022]
Abstract
In recent years, our understanding of the structure, mechanisms and functions of the endo-lysosomal TPC (two-pore channel) family have grown apace. Gated by the second messengers, NAADP and PI(3,5)P2, TPCs are an integral part of fundamental signal-transduction pathways, but their array and plasticity of cation conductances (Na+, Ca2+, H+) allow them to variously signal electrically, osmotically or chemically. Their relative tissue- and organelle-selective distribution, together with agonist-selective ion permeabilities provides a rich palette from which extracellular stimuli can choose. TPCs are emerging as mediators of immunity, cancer, metabolism, viral infectivity and neurodegeneration as this short review attests.
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33
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Patel S, Yuan Y, Chen CC, Jaślan D, Gunaratne G, Grimm C, Rahman T, Marchant JS. Electrophysiology of Endolysosomal Two-Pore Channels: A Current Account. Cells 2022; 11:2368. [PMID: 35954212 PMCID: PMC9368155 DOI: 10.3390/cells11152368] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/20/2022] [Accepted: 07/20/2022] [Indexed: 12/10/2022] Open
Abstract
Two-pore channels TPC1 and TPC2 are ubiquitously expressed pathophysiologically relevant proteins that reside on endolysosomal vesicles. Here, we review the electrophysiology of these channels. Direct macroscopic recordings of recombinant TPCs expressed in enlarged lysosomes in mammalian cells or vacuoles in plants and yeast demonstrate gating by the Ca2+-mobilizing messenger NAADP and/or the lipid PI(3,5)P2. TPC currents are regulated by H+, Ca2+, and Mg2+ (luminal and/or cytosolic), as well as protein kinases, and they are impacted by single-nucleotide polymorphisms linked to pigmentation. Bisbenzylisoquinoline alkaloids, flavonoids, and several approved drugs demonstrably block channel activity. Endogenous TPC currents have been recorded from a number of primary cell types and cell lines. Many of the properties of endolysosomal TPCs are recapitulated upon rerouting channels to the cell surface, allowing more facile recording through conventional electrophysiological means. Single-channel analyses have provided high-resolution insight into both monovalent and divalent permeability. The discovery of small-molecule activators of TPC2 that toggle the ion selectivity from a Ca2+-permeable (NAADP-like) state to a Na+-selective (PI(3,5)P2-like) state explains discrepancies in the literature relating to the permeability of TPCs. Identification of binding proteins that confer NAADP-sensitive currents confirm that indirect, remote gating likely underpins the inconsistent observations of channel activation by NAADP.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK;
| | - Yu Yuan
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK;
| | - Cheng-Chang Chen
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei 100229, Taiwan;
- Department of Laboratory Medicine, National Taiwan University Hospital, Taipei 100225, Taiwan
| | - Dawid Jaślan
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians University, 80336 Munich, Germany; (D.J.); (C.G.)
| | - Gihan Gunaratne
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA; (G.G.); (J.S.M.)
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians University, 80336 Munich, Germany; (D.J.); (C.G.)
| | - Taufiq Rahman
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK;
| | - Jonathan S. Marchant
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA; (G.G.); (J.S.M.)
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34
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The Three Two-Pore Channel Subtypes from Rabbit Exhibit Distinct Sensitivity to Phosphoinositides, Voltage, and Extracytosolic pH. Cells 2022; 11:cells11132006. [PMID: 35805090 PMCID: PMC9265530 DOI: 10.3390/cells11132006] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/17/2022] [Accepted: 06/19/2022] [Indexed: 01/14/2023] Open
Abstract
Two pore channels (TPCs) are implicated in vesicle trafficking, virus infection, and autophagy regulation. As Na+- or Ca2+-permeable channels, TPCs have been reported to be activated by NAADP, PI(3,5)P2, and/or high voltage. However, a comparative study on the function and regulation of the three mammalian TPC subtypes is currently lacking. Here, we used the electrophysiological recording of enlarged endolysosome vacuoles, inside-out and outside-out membrane patches to examine the three TPCs of rabbit (Oryctolagus cuniculus, or Oc) heterologously expressed in HEK293 cells. While PI(3,5)P2 evoked Na+ currents with a potency order of OcTPC1 > OcTPC3 > OcTPC2, only OcTPC2 displayed a strict dependence on PI(3,5)P2. Both OcTPC1 and OcTPC3 were activatable by PI3P and OcTPC3 was also activated by additional phosphoinositide species. While OcTPC2 was voltage-independent, OcTPC1 and OcTPC3 showed voltage dependence with OcTPC3 depending on high positive voltages. Finally, while OcTPC2 preferred a luminal pH of 4.6−6.0 in endolysosomes, OcTPC1 was strongly inhibited by extracytosolic pH 5.0 in both voltage-dependent and -independent manners, and OcTPC3 was inhibited by pH 6.0 but potentiated by pH 8.0. Thus, the three OcTPCs form phosphoinositide-activated Na+ channels with different ligand selectivity, voltage dependence, and extracytosolic pH sensitivity, which likely are optimally tuned for function in specific endolysosomal populations.
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35
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Shah KR, Guan X, Yan J. Diversity of two-pore channels and the accessory NAADP receptors in intracellular Ca 2+ signaling. Cell Calcium 2022; 104:102594. [PMID: 35561646 PMCID: PMC9645597 DOI: 10.1016/j.ceca.2022.102594] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/10/2022] [Accepted: 05/04/2022] [Indexed: 02/03/2023]
Abstract
Intracellular Ca2+ signaling via changes or oscillation in cytosolic Ca2+ concentration controls almost every aspect of cellular function and physiological processes, such as gene transcription, cell motility and proliferation, muscle contraction, and learning and memory. Two-pore channels (TPCs) are a class of eukaryotic cation channels involved in intracellular Ca2+ signaling, likely present in a multitude of organisms from unicellular organisms to mammals. Accumulated evidence indicates that TPCs play a critical role in Ca2+ mobilization from intracellular stores mediated by the second messenger molecule, nicotinic acid adenine dinucleotide phosphate (NAADP). In recent years, significant progress has been made regarding our understanding of the structures and function of TPCs, including Cryo-EM structure determination of mammalian TPCs and characterization of a plastid TPC in a single-celled parasite.. The recent identification of Lsm12 and JPT2 as NAADP-binding proteins provides a new molecular basis for understanding NAADP-evoked Ca2+ signaling. In this review, we summarize basic structural and functional aspects of TPCs and highlight the most recent studies on the newly discovered TPC in a parasitic protozoan and the NAADP-binding proteins LSM12 and JPT2 as new key players in NAADP signaling.
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Affiliation(s)
- Kunal R. Shah
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Xin Guan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA,Neuroscience and Biochemistry and Cell Biology Programs, The University of Texas MD Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, TX, USA,Corresponding author at: Department of Anesthesiology & Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA., (J. Yan)
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36
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Steiner P, Arlt E, Boekhoff I, Gudermann T, Zierler S. Two-Pore Channels Regulate Inter-Organellar Ca 2+ Homeostasis in Immune Cells. Cells 2022; 11:1465. [PMID: 35563771 PMCID: PMC9103377 DOI: 10.3390/cells11091465] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/13/2022] [Accepted: 04/16/2022] [Indexed: 02/01/2023] Open
Abstract
Two-pore channels (TPCs) are ligand-gated cation-selective ion channels that are preserved in plant and animal cells. In the latter, TPCs are located in membranes of acidic organelles, such as endosomes, lysosomes, and endolysosomes. Here, we focus on the function of these unique ion channels in mast cells, which are leukocytes that mature from myeloid hematopoietic stem cells. The cytoplasm of these innate immune cells contains a large number of granules that comprise messenger substances, such as histamine and heparin. Mast cells, along with basophil granulocytes, play an essential role in anaphylaxis and allergic reactions by releasing inflammatory mediators. Signaling in mast cells is mainly regulated via the release of Ca2+ from the endoplasmic reticulum as well as from acidic compartments, such as endolysosomes. For the crosstalk of these organelles TPCs seem essential. Allergic reactions and anaphylaxis were previously shown to be associated with the endolysosomal two-pore channel TPC1. The release of histamine, controlled by intracellular Ca2+ signals, was increased upon genetic or pharmacologic TPC1 inhibition. Conversely, stimulation of TPC channel activity by one of its endogenous ligands, namely nicotinic adenine dinucleotide phosphate (NAADP) or phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2), were found to trigger the release of Ca2+ from the endolysosomes; thereby improving the effect of TPC1 on regulated mast cell degranulation. In this review we discuss the importance of TPC1 for regulating Ca2+ homeostasis in mast cells and the overall potential of TPC1 as a pharmacological target in anti-inflammatory therapy.
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Affiliation(s)
- Philip Steiner
- Institute of Pharmacology, Medical Faculty, Johannes Kepler University Linz, 4020 Linz, Austria;
| | - Elisabeth Arlt
- Walther Straub Institute of Pharmacology and Toxicology, Medical Faculty, Ludwig Maximilians University Munich, 80336 Munich, Germany; (E.A.); (I.B.); (T.G.)
| | - Ingrid Boekhoff
- Walther Straub Institute of Pharmacology and Toxicology, Medical Faculty, Ludwig Maximilians University Munich, 80336 Munich, Germany; (E.A.); (I.B.); (T.G.)
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Medical Faculty, Ludwig Maximilians University Munich, 80336 Munich, Germany; (E.A.); (I.B.); (T.G.)
| | - Susanna Zierler
- Institute of Pharmacology, Medical Faculty, Johannes Kepler University Linz, 4020 Linz, Austria;
- Walther Straub Institute of Pharmacology and Toxicology, Medical Faculty, Ludwig Maximilians University Munich, 80336 Munich, Germany; (E.A.); (I.B.); (T.G.)
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Chen CC, Krogsaeter E, Kuo CY, Huang MC, Chang SY, Biel M. Endolysosomal cation channels point the way towards precision medicine of cancer and infectious diseases. Biomed Pharmacother 2022; 148:112751. [PMID: 35240524 DOI: 10.1016/j.biopha.2022.112751] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 11/02/2022] Open
Abstract
Infectious diseases and cancer are among the key medical challenges that humankind is facing today. A growing amount of evidence suggests that ion channels in the endolysosomal system play a crucial role in the pathology of both groups of diseases. The development of advanced patch-clamp technologies has allowed us to directly characterize ion fluxes through endolysosomal ion channels in their native environments. Endolysosomes are essential organelles for intracellular transport, digestion and metabolism, and maintenance of homeostasis. The endolysosomal ion channels regulate the function of the endolysosomal system through four basic mechanisms: calcium release, control of membrane potential, pH change, and osmolarity regulation. In this review, we put particular emphasis on the endolysosomal cation channels, including TPC2 and TRPML2, which are particularly important in monocyte function. We discuss existing endogenous and synthetic ligands of these channels and summarize current knowledge of their impact on channel activity and function in different cell types. Moreover, we summarize recent findings on the importance of TPC2 and TRPML2 channels as potential drug targets for the prevention and treatment of the emerging infectious diseases and cancer.
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Affiliation(s)
- Cheng-Chang Chen
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan.
| | | | - Ching-Ying Kuo
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Min-Chuan Huang
- Graduate Institute of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Sui-Yuan Chang
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Martin Biel
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
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Current Methods to Unravel the Functional Properties of Lysosomal Ion Channels and Transporters. Cells 2022; 11:cells11060921. [PMID: 35326372 PMCID: PMC8946281 DOI: 10.3390/cells11060921] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/04/2022] [Accepted: 03/05/2022] [Indexed: 02/07/2023] Open
Abstract
A distinct set of channels and transporters regulates the ion fluxes across the lysosomal membrane. Malfunctioning of these transport proteins and the resulting ionic imbalance is involved in various human diseases, such as lysosomal storage disorders, cancer, as well as metabolic and neurodegenerative diseases. As a consequence, these proteins have stimulated strong interest for their suitability as possible drug targets. A detailed functional characterization of many lysosomal channels and transporters is lacking, mainly due to technical difficulties in applying the standard patch-clamp technique to these small intracellular compartments. In this review, we focus on current methods used to unravel the functional properties of lysosomal ion channels and transporters, stressing their advantages and disadvantages and evaluating their fields of applicability.
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39
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Gunaratne GS, Marchant JS. The ins and outs of virus trafficking through acidic Ca 2+ stores. Cell Calcium 2022; 102:102528. [PMID: 35033909 PMCID: PMC8860173 DOI: 10.1016/j.ceca.2022.102528] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 12/20/2022]
Abstract
Many viruses exploit host-cell Ca2+ signaling processes throughout their life cycle. This is especially relevant for viruses that translocate through the endolysosomal system, where cellular infection is keyed to the microenvironment of these acidic Ca2+ stores and Ca2+-dependent trafficking pathways. As regulators of the endolysosomal ionic milieu and trafficking dynamics, two families of endolysosomal Ca2+-permeable cation channels - two pore channels (TPCs) and transient receptor potential mucolipins (TRPMLs) - have emerged as important host-cell factors in viral entry. Here, we review: (i) current evidence implicating Ca2+ signaling in viral translocation through the endolysosomal system, (ii) the roles of these ion channels in supporting cellular infection by different viruses, and (iii) areas for future research that will help define the potential of TPC and TRPML ligands as progressible antiviral agents.
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Affiliation(s)
- Gihan S Gunaratne
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee WI 53226, USA.
| | - Jonathan S Marchant
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee WI 53226, USA
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40
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Marchant JS, Gunaratne GS, Cai X, Slama JT, Patel S. NAADP-binding proteins find their identity. Trends Biochem Sci 2022; 47:235-249. [PMID: 34810081 PMCID: PMC8840967 DOI: 10.1016/j.tibs.2021.10.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 10/19/2021] [Accepted: 10/26/2021] [Indexed: 02/07/2023]
Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a second messenger that releases Ca2+ from endosomes and lysosomes by activating ion channels called two-pore channels (TPCs). However, no NAADP-binding site has been identified on TPCs. Rather, NAADP activates TPCs indirectly by engaging NAADP-binding proteins (NAADP-BPs) that form part of the TPC complex. After a decade of searching, two different NAADP-BPs were recently identified: Jupiter microtubule associated homolog 2 (JPT2) and like-Sm protein 12 (LSM12). These discoveries bridge the gap between NAADP generation and NAADP activation of TPCs, providing new opportunity to understand and manipulate the NAADP-signaling pathway. The unmasking of these NAADP-BPs will catalyze future studies to define the molecular choreography of NAADP action.
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Affiliation(s)
- Jonathan S. Marchant
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA,Correspondence: (J.S. Marchant) and (S. Patel)
| | - Gihan S. Gunaratne
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Xinjiang Cai
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - James T. Slama
- Department of Medicinal and Biological Chemistry, University of Toledo College of Pharmacy and Pharmaceutical Sciences, 3000 Arlington Avenue, Toledo, OH 43614, USA
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
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41
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Dickinson MS, Lu J, Gupta M, Marten I, Hedrich R, Stroud RM. Molecular basis of multistep voltage activation in plant two-pore channel 1. Proc Natl Acad Sci U S A 2022; 119:e2110936119. [PMID: 35210362 PMCID: PMC8892357 DOI: 10.1073/pnas.2110936119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 11/29/2021] [Indexed: 12/26/2022] Open
Abstract
Voltage-gated ion channels confer excitability to biological membranes, initiating and propagating electrical signals across large distances on short timescales. Membrane excitation requires channels that respond to changes in electric field and couple the transmembrane voltage to gating of a central pore. To address the mechanism of this process in a voltage-gated ion channel, we determined structures of the plant two-pore channel 1 at different stages along its activation coordinate. These high-resolution structures of activation intermediates, when compared with the resting-state structure, portray a mechanism in which the voltage-sensing domain undergoes dilation and in-membrane plane rotation about the gating charge-bearing helix, followed by charge translocation across the charge transfer seal. These structures, in concert with patch-clamp electrophysiology, show that residues in the pore mouth sense inhibitory Ca2+ and are allosterically coupled to the voltage sensor. These conformational changes provide insight into the mechanism of voltage-sensor domain activation in which activation occurs vectorially over a series of elementary steps.
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Affiliation(s)
- Miles Sasha Dickinson
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
- Chemistry and Chemical Biology Graduate Program, University of California, San Francisco, CA 94143
| | - Jinping Lu
- Department of Molecular Plant Physiology and Biophysics, University of Würzburg, D-97082 Würzburg, Germany
| | - Meghna Gupta
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
| | - Irene Marten
- Department of Molecular Plant Physiology and Biophysics, University of Würzburg, D-97082 Würzburg, Germany
| | - Rainer Hedrich
- Department of Molecular Plant Physiology and Biophysics, University of Würzburg, D-97082 Würzburg, Germany
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143;
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Yamamori Y, Tomii K. Application of Homology Modeling by Enhanced Profile-Profile Alignment and Flexible-Fitting Simulation to Cryo-EM Based Structure Determination. Int J Mol Sci 2022; 23:ijms23041977. [PMID: 35216093 PMCID: PMC8879198 DOI: 10.3390/ijms23041977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 12/03/2022] Open
Abstract
Application of cryo-electron microscopy (cryo-EM) is crucially important for ascertaining the atomic structure of large biomolecules such as ribosomes and protein complexes in membranes. Advances in cryo-EM technology and software have made it possible to obtain data with near-atomic resolution, but the method is still often capable of producing only a density map with up to medium resolution, either partially or entirely. Therefore, bridging the gap separating the density map and the atomic model is necessary. Herein, we propose a methodology for constructing atomic structure models based on cryo-EM maps with low-to-medium resolution. The method is a combination of sensitive and accurate homology modeling using our profile–profile alignment method with a flexible-fitting method using molecular dynamics simulation. As described herein, this study used benchmark applications to evaluate the model constructions of human two-pore channel 2 (one target protein in CASP13 with its structure determined using cryo-EM data) and the overall structure of Enterococcus hirae V-ATPase complex.
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Affiliation(s)
- Yu Yamamori
- Artificial Intelligence Research Center (AIRC), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan;
| | - Kentaro Tomii
- Artificial Intelligence Research Center (AIRC), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan;
- AIST-Tokyo Tech Real World Big-Data Computation Open Innovation Laboratory (RWBC-OIL), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
- Correspondence:
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43
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Krogsaeter E, Rosato AS, Grimm C. TRPMLs and TPCs: targets for lysosomal storage and neurodegenerative disease therapy? Cell Calcium 2022; 103:102553. [DOI: 10.1016/j.ceca.2022.102553] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 12/25/2022]
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Giridharan SSP, Luo G, Rivero-Rios P, Steinfeld N, Tronchere H, Singla A, Burstein E, Billadeau DD, Sutton MA, Weisman LS. Lipid kinases VPS34 and PIKfyve coordinate a phosphoinositide cascade to regulate Retriever-mediated recycling on endosomes. eLife 2022; 11:69709. [PMID: 35040777 PMCID: PMC8816382 DOI: 10.7554/elife.69709] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 01/17/2022] [Indexed: 11/13/2022] Open
Abstract
Cell-surface receptors control how cells respond to their environment. Many cell-surface receptors recycle from endosomes to the plasma membrane via a recently discovered pathway, which includes sorting-nexin SNX17, Retriever, WASH and CCC complexes. Here, using mammalian cells, we discover that PIKfyve and its upstream PI3-kinase VPS34 positively regulate this pathway. VPS34 produces PI3P, which is the substrate for PIKfyve to generate PI3,5P2. We show that PIKfyve controls recycling of cargoes including integrins, receptors that control cell migration. Furthermore, endogenous PIKfyve colocalizes with SNX17, Retriever, WASH and CCC complexes on endosomes. Importantly, PIKfyve inhibition results displacement of Retriever and CCC from endosomes. In addition, we show that recruitment of SNX17 is an early step and requires VPS34. These discoveries suggest that VPS34 and PIKfyve coordinate an ordered pathway to regulate recycling from endosomes and suggest how PIKfyve functions in cell migration.
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Affiliation(s)
| | - Guangming Luo
- Department of Cell and Developmental Biology, University of Michigan-Ann Arbor
| | - Pilar Rivero-Rios
- Department of Cell and Developmental Biology, University of Michigan-Ann Arbor
| | - Noah Steinfeld
- Department of Cell and Developmental Biology, University of Michigan-Ann Arbor
| | | | - Amika Singla
- Department of Internal Medicine, The University of Texas Southwestern Medical Center
| | - Ezra Burstein
- Department of Internal Medicine, The University of Texas Southwestern Medical Center
| | | | - Michael A Sutton
- Molecular and Integrative Physiology, University of Michigan-Ann Arbor
| | - Lois S Weisman
- Department of Cell and Developmental Biology, University of Michigan-Ann Arbor
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45
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Barbonari S, D'Amore A, Palombi F, De Cesaris P, Parrington J, Riccioli A, Filippini A. RELEVANCE OF LYSOSOMAL Ca2+ SIGNALLING MACHINERY IN CANCER. Cell Calcium 2022; 102:102539. [DOI: 10.1016/j.ceca.2022.102539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 12/23/2022]
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46
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Activation of endo-lysosomal two-pore channels by NAADP and PI(3,5)P2. Five things to know. Cell Calcium 2022; 103:102543. [PMID: 35123238 PMCID: PMC9552313 DOI: 10.1016/j.ceca.2022.102543] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/21/2022] [Accepted: 01/24/2022] [Indexed: 12/31/2022]
Abstract
Two-pore channels are ancient members of the voltage-gated ion channel superfamily that are expressed predominantly on acidic organelles such as endosomes and lysosomes. Here we review recent advances in understanding how TPCs are activated by their ligands and identify five salient features: (1) TPCs are Ca2+-permeable non-selective cation channels gated by NAADP. (2) NAADP activation is indirect through associated NAADP receptors. (3) TPCs are also Na+-selective channels gated by PI(3,5)P2. (4) PI(3,5)P2 activation is direct through a structurally-resolved binding site. (5) TPCs switch their ion selectivity in an agonist-dependent manner.
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47
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Nicolas C, Zlebnik NE, Farokhnia M, Leggio L, Ikemoto S, Shaham Y. Sex Differences in Opioid and Psychostimulant Craving and Relapse: A Critical Review. Pharmacol Rev 2022; 74:119-140. [PMID: 34987089 PMCID: PMC11060335 DOI: 10.1124/pharmrev.121.000367] [Citation(s) in RCA: 61] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 08/15/2021] [Indexed: 01/11/2023] Open
Abstract
A widely held dogma in the preclinical addiction field is that females are more vulnerable than males to drug craving and relapse. Here, we first review clinical studies on sex differences in psychostimulant and opioid craving and relapse. Next, we review preclinical studies on sex differences in psychostimulant and opioid reinstatement of drug seeking after extinction of drug self-administration, and incubation of drug craving (time-dependent increase in drug seeking during abstinence). We also discuss ovarian hormones' role in relapse and craving in humans and animal models and speculate on brain mechanisms underlying their role in cocaine craving and relapse in rodent models. Finally, we discuss imaging studies on brain responses to cocaine cues and stress in men and women.The results of the clinical studies reviewed do not appear to support the notion that women are more vulnerable to psychostimulant and opioid craving and relapse. However, this conclusion is tentative because most of the studies reviewed were correlational, not sufficiently powered, and not a priori designed to detect sex differences. Additionally, imaging studies suggest sex differences in brain responses to cocaine cues and stress. The results of the preclinical studies reviewed provide evidence for sex differences in stress-induced reinstatement and incubation of cocaine craving but not cue- or cocaine-induced reinstatement of cocaine seeking. These sex differences are modulated in part by ovarian hormones. In contrast, the available data do not support the notion of sex differences in craving and relapse/reinstatement for methamphetamine or opioids in rodent models. SIGNIFICANCE STATEMENT: This systematic review summarizes clinical and preclinical studies on sex differences in psychostimulant and opioid craving and relapse. Results of the clinical studies reviewed do not appear to support the notion that women are more vulnerable to psychostimulant and opioid craving and relapse. Results of preclinical studies reviewed provide evidence for sex differences in reinstatement and incubation of cocaine seeking but not for reinstatement or incubation of methamphetamine or opioid seeking.
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Affiliation(s)
- Céline Nicolas
- Neurocentre Magendie, University of Bordeaux, Bordeaux, France (C.N.); Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, Present address: Division of Biomedical Sciences, University of California Riverside, School of Medicine, Riverside, CA (N.E.Z.); Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD (M.F., L.L., S.I., Y.S.); and Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD (M.F., L.L.)
| | - Natalie E Zlebnik
- Neurocentre Magendie, University of Bordeaux, Bordeaux, France (C.N.); Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, Present address: Division of Biomedical Sciences, University of California Riverside, School of Medicine, Riverside, CA (N.E.Z.); Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD (M.F., L.L., S.I., Y.S.); and Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD (M.F., L.L.)
| | - Mehdi Farokhnia
- Neurocentre Magendie, University of Bordeaux, Bordeaux, France (C.N.); Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, Present address: Division of Biomedical Sciences, University of California Riverside, School of Medicine, Riverside, CA (N.E.Z.); Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD (M.F., L.L., S.I., Y.S.); and Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD (M.F., L.L.)
| | - Lorenzo Leggio
- Neurocentre Magendie, University of Bordeaux, Bordeaux, France (C.N.); Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, Present address: Division of Biomedical Sciences, University of California Riverside, School of Medicine, Riverside, CA (N.E.Z.); Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD (M.F., L.L., S.I., Y.S.); and Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD (M.F., L.L.)
| | - Satoshi Ikemoto
- Neurocentre Magendie, University of Bordeaux, Bordeaux, France (C.N.); Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, Present address: Division of Biomedical Sciences, University of California Riverside, School of Medicine, Riverside, CA (N.E.Z.); Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD (M.F., L.L., S.I., Y.S.); and Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD (M.F., L.L.)
| | - Yavin Shaham
- Neurocentre Magendie, University of Bordeaux, Bordeaux, France (C.N.); Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, Present address: Division of Biomedical Sciences, University of California Riverside, School of Medicine, Riverside, CA (N.E.Z.); Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD (M.F., L.L., S.I., Y.S.); and Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD (M.F., L.L.)
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48
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Gan N, Jiang Y. Structural biology of cation channels important for lysosomal calcium release. Cell Calcium 2022; 101:102519. [PMID: 34952412 PMCID: PMC8752501 DOI: 10.1016/j.ceca.2021.102519] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/10/2021] [Accepted: 12/11/2021] [Indexed: 01/03/2023]
Abstract
Calcium is one of the most important second messengers in cells. The uptake and release of calcium ions are conducted by channels and transporters. Inside a eukaryotic cell, calcium is stored in intracellular organelles including the endoplasmic reticulum (ER), mitochondrion, and lysosome. Lysosomes are acid membrane-bounded organelles serving as the crucial degradation and recycling center of the cell. Lysosomes involve in multiple important signaling events, including nutrient sensing, lipid metabolism, and trafficking. Hitherto, two lysosomal cation channel families have been suggested to function as calcium release channels, namely the Two-pore Channel (TPC) family, and the Transient Receptor Potential Channel Mucolipin (TRPML) family. Additionally, a few plasma membrane calcium channels have also been found in the lysosomal membrane under certain circumstances. In this review, we will discuss the structural mechanism of the cation channels that may be important for lysosomal calcium release, primarily focusing on the TPCs and TRPMLs.
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Affiliation(s)
- Ninghai Gan
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390 USA,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390 USA
| | - Youxing Jiang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390 USA,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390 USA
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49
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Fractalkine-induced microglial vasoregulation occurs within the retina and is altered early in diabetic retinopathy. Proc Natl Acad Sci U S A 2021; 118:2112561118. [PMID: 34903661 PMCID: PMC8713803 DOI: 10.1073/pnas.2112561118] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2021] [Indexed: 01/19/2023] Open
Abstract
This work identifies a role for microglia, the innate immune cells of the CNS, in the local control of the retinal vasculature and identifies deficits early in diabetes. Microglia contact neurons and vasculature and express several vasoactive agents. Activation of microglial fractalkine-Cx3cr1 signaling leads to capillary constriction and blocking the renin-angiotensin system (RAS) with candesartan abolishes microglial-mediated vasoconstriction in the retina. In early diabetes, reduced retinal blood flow is coincident with capillary constriction, increased microglial–vessel association, loss of microglial–capillary regulation, and altered microglial expression of the RAS pathway. While candesartan restores retinal capillary diameter early in diabetes, targeting of microglial–vascular regulation is required to prevent coincident dilation of large retinal vessels and reduced retinal blood flow. Local blood flow control within the central nervous system (CNS) is critical to proper function and is dependent on coordination between neurons, glia, and blood vessels. Macroglia, such as astrocytes and Müller cells, contribute to this neurovascular unit within the brain and retina, respectively. This study explored the role of microglia, the innate immune cell of the CNS, in retinal vasoregulation, and highlights changes during early diabetes. Structurally, microglia were found to contact retinal capillaries and neuronal synapses. In the brain and retinal explants, the addition of fractalkine, the sole ligand for monocyte receptor Cx3cr1, resulted in capillary constriction at regions of microglial contact. This vascular regulation was dependent on microglial Cx3cr1 involvement, since genetic and pharmacological inhibition of Cx3cr1 abolished fractalkine-induced constriction. Analysis of the microglial transcriptome identified several vasoactive genes, including angiotensinogen, a constituent of the renin-angiotensin system (RAS). Subsequent functional analysis showed that RAS blockade via candesartan abolished microglial-induced capillary constriction. Microglial regulation was explored in a rat streptozotocin (STZ) model of diabetic retinopathy. Retinal blood flow was reduced after 4 wk due to reduced capillary diameter and this was coincident with increased microglial association. Functional assessment showed loss of microglial–capillary response in STZ-treated animals and transcriptome analysis showed evidence of RAS pathway dysregulation in microglia. While candesartan treatment reversed capillary constriction in STZ-treated animals, blood flow remained decreased likely due to dilation of larger vessels. This work shows microglia actively participate in the neurovascular unit, with aberrant microglial–vascular function possibly contributing to the early vascular compromise during diabetic retinopathy.
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Voltage-gating and cytosolic Ca 2+ activation mechanisms of Arabidopsis two-pore channel AtTPC1. Proc Natl Acad Sci U S A 2021; 118:2113946118. [PMID: 34845029 DOI: 10.1073/pnas.2113946118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2021] [Indexed: 11/18/2022] Open
Abstract
Arabidopsis thaliana two-pore channel AtTPC1 is a voltage-gated, Ca2+-modulated, nonselective cation channel that is localized in the vacuolar membrane and responsible for generating slow vacuolar (SV) current. Under depolarizing membrane potential, cytosolic Ca2+ activates AtTPC1 by binding at the EF-hand domain, whereas luminal Ca2+ inhibits the channel by stabilizing the voltage-sensing domain II (VSDII) in the resting state. Here, we present 2.8 to 3.3 Å cryoelectron microscopy (cryo-EM) structures of AtTPC1 in two conformations, one in closed conformation with unbound EF-hand domain and resting VSDII and the other in a partially open conformation with Ca2+-bound EF-hand domain and activated VSDII. Structural comparison between the two different conformations allows us to elucidate the structural mechanisms of voltage gating, cytosolic Ca2+ activation, and their coupling in AtTPC1. This study also provides structural insight into the general voltage-gating mechanism among voltage-gated ion channels.
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