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Hu M, Feng X, Liu Q, Liu S, Huang F, Xu H. The Ion Channels of Endomembranes. Physiol Rev 2024. [PMID: 38451235 DOI: 10.1152/physrev.00025.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [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, luminal and juxta-organellar 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 understandings 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
- School of Medicine, Zhejiang University, Hangzhou, China
| | - Xinghua Feng
- Neurology, Second Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Qiang Liu
- School of medicine, Zhejiang University, Hangzhou, China
| | - Siyu Liu
- School of Medicine, Zhejiang University, Hangzhou, China
| | - Fangqian Huang
- School of Medicine, Zhejiang University, Hangzhou, China
| | - Haoxing Xu
- New Cornerstone Science Laboratory, Liangzhu Institute & School of Basic Medical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
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Yang C, Tian F, Hu M, Kang C, Ping M, Liu Y, Hu M, Xu H, Yu Y, Gao Z, Li P. Characterization of the role of TMEM175 in an in vitro lysosomal H + fluxes model. FEBS J 2023; 290:4641-4659. [PMID: 37165739 DOI: 10.1111/febs.16814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/06/2023] [Accepted: 05/09/2023] [Indexed: 05/12/2023]
Abstract
Lysosome acidification is a dynamic equilibrium of H+ influx and efflux across the membrane, which is crucial for cell physiology. The vacuolar H+ ATPase (V-ATPase) is responsible for the H+ influx or refilling of lysosomes. TMEM175 was identified as a novel H+ permeable channel on lysosomal membranes, and it plays a critical role in lysosome acidification. However, how TMEM175 participates in lysosomal acidification remains unknown. Here, we present evidence that TMEM175 regulates lysosomal H+ influx and efflux in enlarged lysosomes isolated from COS1 treated with vacuolin-1. By utilizing the whole-endolysosome patch-clamp recording technique, a series of integrated lysosomal H+ influx and efflux signals in a ten-of-second time scale under the physiological pH gradient (luminal pH 4.60, and cytosolic pH 7.20) was recorded from this in vitro system. Lysosomal H+ fluxes constitute both the lysosomal H+ refilling and releasing, and they are asymmetrical processes with distinct featured kinetics for each of the H+ fluxes. Lysosomal H+ fluxes are entirely abolished when TMEM175 losses of function in the F39V mutant and is blocked by the antagonist (2-GBI). Meanwhile, lysosomal H+ fluxes are modulated by the pH-buffering capacity of the lumen and the lysosomal glycosylated membrane proteins, lysosome-associated membrane protein 1 (LAMP1). We propose that the TMEM175-mediated lysosomal H+ fluxes model would provide novel thoughts for studying the pathology of Parkinson's disease and lysosome storage disorders.
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Affiliation(s)
- Chuanyan Yang
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Fuyun Tian
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
| | - Mei Hu
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- Pharmacology Laboratory, Zhongshan Hospital, Guangzhou University of Chinese Medicine, China
| | - Chunlan Kang
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China
| | - Meixuan Ping
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yiyao Liu
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
| | - Meiqin Hu
- Department of Molecular, Cellular, and Developmental Biology, The University of Michigan, Ann Arbor, Michigan, USA
| | - Haoxing Xu
- Department of Molecular, Cellular, and Developmental Biology, The University of Michigan, Ann Arbor, Michigan, USA
| | - Ye Yu
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Zhaobing Gao
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ping Li
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
- University of Chinese Academy of Sciences, Beijing, China
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3
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Wang Y, Li W, Wang Q. Lysosome pH-regulated H + /K + switching channel involved in maintaining lysosomal homeostasis. FEBS J 2023; 290:4638-4640. [PMID: 37434434 DOI: 10.1111/febs.16895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 07/03/2023] [Indexed: 07/13/2023]
Abstract
Lysosomal pH setpoint and H+ homeostasis is key to the lysosome's functions. The Parkinson's disease-risk protein TMEM175, originally identified as lysosomal K+ channel, works as a H+ -activated H+ channel and discharges the lysosomal H+ store when it is hyper-acidified. Yang et al. indicate that TMEM175 is permeable for both K+ and H+ in the same pore and charges the lysosome with H+ under certain conditions. The charge and discharge functions are under regulation of the lysosomal matrix and glycocalyx layer. Their presented work indicates that TMEM175 performs as a multi-functional channel regulating lysosomal pH in response to physiological conditions.
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Affiliation(s)
- Yizhen Wang
- Beijing Key Laboratory for Genetics of Birth Defects, Beijing Pediatric Research Institute, China
- MOE Key Laboratory of Major Diseases in Children, Capital Medical University, Beijing, China
- Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Wei Li
- Beijing Key Laboratory for Genetics of Birth Defects, Beijing Pediatric Research Institute, China
- MOE Key Laboratory of Major Diseases in Children, Capital Medical University, Beijing, China
- Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Qiaochu Wang
- Beijing Key Laboratory for Genetics of Birth Defects, Beijing Pediatric Research Institute, China
- MOE Key Laboratory of Major Diseases in Children, Capital Medical University, Beijing, China
- Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
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Zhang H, Tian Y, Yu W, Tong D, Ji Y, Qu X, Deng T, Li X, Xu Y. TMEM175 downregulation participates in impairment of the autophagy related lysosomal dynamics following neonatal hypoxic-ischemic brain injury. J Cell Physiol 2023; 238:2512-2527. [PMID: 37566721 DOI: 10.1002/jcp.31096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 08/13/2023]
Abstract
The mechanism underlying long-term cognitive impairment caused by neonatal hypoxic-ischemic brain injury (HIBI) remains unclear. Autophagy is a closely related mechanism and may play a role in this process. We aimed to investigate the role of lysosomal transmembrane protein 175 (TMEM175) in the autophagy-lysosome pathway in neonatal rats with HIBI. A neonatal rat model of HIBI was established, hypoxia was induced, followed by left common carotid artery ligation. Expression levels of TMEM175 and the corresponding proteins involved in autophagy flux and the endolysosomal system fusion process were measured. Rats were administered TMEM175 plasmid via intracerebroventricular injection to induce overexpression. Brain damage and cognitive function were then assessed. TMEM175 was downregulated in the hippocampal tissue, and the autophagy-lysosome pathway was impaired following HIBI in neonatal rats. Overexpression of TMEM175 significantly mitigated neuronal injury and improved long-term cognitive and memory function in neonatal rats with HIBI. We found that improvement in the autophagy-lysosome pathway and endolysosomal system homeostasis, which are TMEM175 related, occurred via regulation of lysosomal membrane dynamic fusion. TMEM175 plays a critical role in maintaining the autophagy-lysosome pathway and endolysosomal homeostasis, contributing to the amelioration of neuronal injury and impaired long-term cognitive function following neonatal HIBI.
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Affiliation(s)
- Huiyi Zhang
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Ye Tian
- Department of Orthopedics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Weiwei Yu
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Dongyi Tong
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yichen Ji
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Xinrui Qu
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Tianjiao Deng
- The First Clinical College, China Medical University, Shenyang, China
| | - Xinsheng Li
- The First Clinical College, China Medical University, Shenyang, China
| | - Ying Xu
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
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Wu L, Lin Y, Song J, Li L, Rao X, Wan W, Wei G, Hua F, Ying J. TMEM175: A lysosomal ion channel associated with neurological diseases. Neurobiol Dis 2023; 185:106244. [PMID: 37524211 DOI: 10.1016/j.nbd.2023.106244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/09/2023] [Accepted: 07/28/2023] [Indexed: 08/02/2023] Open
Abstract
Lysosomes are acidic intracellular organelles with autophagic functions that are critical for protein degradation and mitochondrial homeostasis, while abnormalities in lysosomal physiological functions are closely associated with neurological disorders. Transmembrane protein 175 (TMEM175), an ion channel in the lysosomal membrane that is essential for maintaining lysosomal acidity, has been proven to coordinate with V-ATPase to modulate the luminal pH of the lysosome to assist the digestion of abnormal proteins and organelles. However, there is considerable controversy about the characteristics of TMEM175. In this review, we introduce the research progress on the structural, modulatory, and functional properties of TMEM175, followed by evidence of its relevance for neurological disorders. Finally, we discuss the potential value of TMEM175 as a therapeutic target in the hope of providing new directions for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Luojia Wu
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006, Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Privince, China
| | - Yue Lin
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006, Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Privince, China
| | - Jiali Song
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006, Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Privince, China
| | - Longshan Li
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006, Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Privince, China
| | - Xiuqin Rao
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006, Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Privince, China
| | - Wei Wan
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006, Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Privince, China
| | - Gen Wei
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006, Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Privince, China
| | - Fuzhou Hua
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006, Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Privince, China.
| | - Jun Ying
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006, Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Privince, China.
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Bazzone A, Barthmes M, George C, Brinkwirth N, Zerlotti R, Prinz V, Cole K, Friis S, Dickson A, Rice S, Lim J, Fern Toh M, Mohammadi M, Pau D, Stone DJ, Renger JJ, Fertig N. A Comparative Study on the Lysosomal Cation Channel TMEM175 Using Automated Whole-Cell Patch-Clamp, Lysosomal Patch-Clamp, and Solid Supported Membrane-Based Electrophysiology: Functional Characterization and High-Throughput Screening Assay Development. Int J Mol Sci 2023; 24:12788. [PMID: 37628970 PMCID: PMC10454728 DOI: 10.3390/ijms241612788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/09/2023] [Accepted: 08/12/2023] [Indexed: 08/27/2023] Open
Abstract
The lysosomal cation channel TMEM175 is a Parkinson's disease-related protein and a promising drug target. Unlike whole-cell automated patch-clamp (APC), lysosomal patch-clamp (LPC) facilitates physiological conditions, but is not yet suitable for high-throughput screening (HTS) applications. Here, we apply solid supported membrane-based electrophysiology (SSME), which enables both direct access to lysosomes and high-throughput electrophysiological recordings. In SSME, ion translocation mediated by TMEM175 is stimulated using a concentration gradient at a resting potential of 0 mV. The concentration-dependent K+ response exhibited an I/c curve with two distinct slopes, indicating the existence of two conducting states. We measured H+ fluxes with a permeability ratio of PH/PK = 48,500, which matches literature findings from patch-clamp studies, validating the SSME approach. Additionally, TMEM175 displayed a high pH dependence. Decreasing cytosolic pH inhibited both K+ and H+ conductivity of TMEM175. Conversely, lysosomal pH and pH gradients did not have major effects on TMEM175. Finally, we developed HTS assays for drug screening and evaluated tool compounds (4-AP, Zn as inhibitors; DCPIB, arachidonic acid, SC-79 as enhancers) using SSME and APC. Additionally, we recorded EC50 data for eight blinded TMEM175 enhancers and compared the results across all three assay technologies, including LPC, discussing their advantages and disadvantages.
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Affiliation(s)
- Andre Bazzone
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Maria Barthmes
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Cecilia George
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Nina Brinkwirth
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Rocco Zerlotti
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
- RIGeL-Regensburg International Graduate School of Life Sciences, University of Regensburg, 93053 Regensburg, Germany
| | - Valentin Prinz
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Kim Cole
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Søren Friis
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Alexander Dickson
- SB Drug Discovery, West of Scotland Science Park, Glasgow G20 0XA, UK; (A.D.); (S.R.)
| | - Simon Rice
- SB Drug Discovery, West of Scotland Science Park, Glasgow G20 0XA, UK; (A.D.); (S.R.)
| | - Jongwon Lim
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | - May Fern Toh
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | | | - Davide Pau
- SB Drug Discovery, West of Scotland Science Park, Glasgow G20 0XA, UK; (A.D.); (S.R.)
| | - David J. Stone
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | - John J. Renger
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | - Niels Fertig
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
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Zhang J, Zeng W, Han Y, Lee WR, Liou J, Jiang Y. Lysosomal LAMP proteins regulate lysosomal pH by direct inhibition of the TMEM175 channel. Mol Cell 2023; 83:2524-2539.e7. [PMID: 37390818 PMCID: PMC10528928 DOI: 10.1016/j.molcel.2023.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 04/03/2023] [Accepted: 06/02/2023] [Indexed: 07/02/2023]
Abstract
Maintaining a highly acidic lysosomal pH is central to cellular physiology. Here, we use functional proteomics, single-particle cryo-EM, electrophysiology, and in vivo imaging to unravel a key biological function of human lysosome-associated membrane proteins (LAMP-1 and LAMP-2) in regulating lysosomal pH homeostasis. Despite being widely used as a lysosomal marker, the physiological functions of the LAMP proteins have long been overlooked. We show that LAMP-1 and LAMP-2 directly interact with and inhibit the activity of the lysosomal cation channel TMEM175, a key player in lysosomal pH homeostasis implicated in Parkinson's disease. This LAMP inhibition mitigates the proton conduction of TMEM175 and facilitates lysosomal acidification to a lower pH environment crucial for optimal hydrolase activity. Disrupting the LAMP-TMEM175 interaction alkalinizes the lysosomal pH and compromises the lysosomal hydrolytic function. In light of the ever-increasing importance of lysosomes to cellular physiology and diseases, our data have widespread implications for lysosomal biology.
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Affiliation(s)
- Jiyuan Zhang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Weizhong Zeng
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA; Howard Hughes Medical Institute at University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yan Han
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Wan-Ru Lee
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jen Liou
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Youxing Jiang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA; Howard Hughes Medical Institute at University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Tang T, Jian B, Liu Z. Transmembrane Protein 175, a Lysosomal Ion Channel Related to Parkinson's Disease. Biomolecules 2023; 13:biom13050802. [PMID: 37238672 DOI: 10.3390/biom13050802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/14/2023] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
Lysosomes are membrane-bound organelles with an acidic lumen and are traditionally characterized as a recycling center in cells. Lysosomal ion channels are integral membrane proteins that form pores in lysosomal membranes and allow the influx and efflux of essential ions. Transmembrane protein 175 (TMEM175) is a unique lysosomal potassium channel that shares little sequence similarity with other potassium channels. It is found in bacteria, archaea, and animals. The prokaryotic TMEM175 consists of one six-transmembrane domain that adopts a tetrameric architecture, while the mammalian TMEM175 is comprised of two six-transmembrane domains that function as a dimer in lysosomal membranes. Previous studies have demonstrated that the lysosomal K+ conductance mediated by TMEM175 is critical for setting membrane potential, maintaining pH stability, and regulating lysosome-autophagosome fusion. AKT and B-cell lymphoma 2 regulate TMEM175's channel activity through direct binding. Two recent studies reported that the human TMEM175 is also a proton-selective channel under normal lysosomal pH (4.5-5.5) as the K+ permeation dramatically decreased at low pH while the H+ current through TMEM175 greatly increased. Genome-wide association studies and functional studies in mouse models have established that TMEM175 is implicated in the pathogenesis of Parkinson's disease, which sparks more research interests in this lysosomal channel.
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Affiliation(s)
- Tuoxian Tang
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Boshuo Jian
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Zhenjiang Liu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
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Hu M, Chen J, Liu S, Xu H. The Acid Gate in the Lysosome. Autophagy 2023; 19:1368-1370. [PMID: 36120744 PMCID: PMC10012942 DOI: 10.1080/15548627.2022.2125629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/10/2022] [Accepted: 09/13/2022] [Indexed: 11/02/2022] Open
Abstract
The acidic environment within lysosomes is maintained within a narrow pH range (pH 4.5-5.0) optimal for digesting autophagic cargo macromolecules so that the resulting building block metabolites can be reused. This pH homeostasis is a consequence of proton influx produced by a V-type H+-translocating ATPase (V-ATPase) and rapid proton efflux through an unidentified "leak" pathway. By performing a candidate expression screening, we discovered that the TMEM175 gene encodes a proton-activated, proton-selective channel (LyPAP) that is required for lysosomal H+ "leak" currents. The activity of LyPAP is most active when lysosomes are hyper-acidified, and cells lacking TMEM175 exhibit lysosomal hyper-acidification and impaired proteolytic degradation, both of which can be restored by optimizing lysosomal pH using pharmacological agents. Variants of TMEM175 that are associated with susceptibility to Parkinson disease (PD) cause a reduction in TMEM175-dependent LyPAP currents and lysosomal hyper-acidification. Hence, our studies not only reveal an essential H+-dissipating pathway in lysosomes, but also provide a molecular target to regulate pH-dependent lysosomal functions and associated pathologies.
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Affiliation(s)
- Meiqin Hu
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, China
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 4114 Biological Sciences Building (BSB), 1105 N. University Ave, Ann Arbor, MI, USA
- Liangzhu Laboratory & Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, China
| | - Jingzhi Chen
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, China
- Liangzhu Laboratory & Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, China
| | - Siyu Liu
- Liangzhu Laboratory & Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, China
| | - Haoxing Xu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 4114 Biological Sciences Building (BSB), 1105 N. University Ave, Ann Arbor, MI, USA
- Liangzhu Laboratory & Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, China
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Palomba NP, Fortunato G, Pepe G, Modugno N, Pietracupa S, Damiano I, Mascio G, Carrillo F, Di Giovannantonio LG, Ianiro L, Martinello K, Volpato V, Desiato V, Acri R, Storto M, Nicoletti F, Webber C, Simeone A, Fucile S, Maglione V, Esposito T. Common and Rare Variants in TMEM175 Gene Concur to the Pathogenesis of Parkinson's Disease in Italian Patients. Mol Neurobiol 2023; 60:2150-2173. [PMID: 36609826 PMCID: PMC9984355 DOI: 10.1007/s12035-022-03203-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 12/21/2022] [Indexed: 01/09/2023]
Abstract
Parkinson's disease (PD) represents the most common neurodegenerative movement disorder. We recently identified 16 novel genes associated with PD. In this study, we focused the attention on the common and rare variants identified in the lysosomal K+ channel TMEM175. The study includes a detailed clinical and genetic analysis of 400 cases and 300 controls. Molecular studies were performed on patient-derived fibroblasts. The functional properties of the mutant channels were assessed by patch-clamp technique and co-immunoprecipitation. We have found that TMEM175 was highly expressed in dopaminergic neurons of the substantia nigra pars compacta and in microglia of the cerebral cortex of the human brain. Four common variants were associated with PD, including two novel variants rs2290402 (c.-10C > T) and rs80114247 (c.T1022C, p.M341T), located in the Kozak consensus sequence and TM3II domain, respectively. We also disclosed 13 novel highly penetrant detrimental mutations in the TMEM175 gene associated with PD. At least nine of these mutations (p.R35C, p. R183X, p.A270T, p.P308L, p.S348L, p. L405V, p.R414W, p.P427fs, p.R481W) may be sufficient to cause the disease, and the presence of mutations of other genes correlated with an earlier disease onset. In vitro functional analysis of the ion channel encoded by the mutated TMEM175 gene revealed a loss of the K+ conductance and a reduced channel affinity for Akt. Moreover, we observed an impaired autophagic/lysosomal proteolytic flux and an increase expression of unfolded protein response markers in patient-derived fibroblasts. These data suggest that mutations in TMEM175 gene may contribute to the pathophysiology of PD.
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Affiliation(s)
| | - Giorgio Fortunato
- Institute of Genetics and Biophysics, Adriano Buzzati-Traverso", National Research Council, Naples, Italy.,Department of Environmental, Biological and Pharmaceutical Sciences and Technologies (DiSTABiF), University of Campania Luigi Vanvitelli, Caserta, Italy
| | | | | | | | - Immacolata Damiano
- Institute of Genetics and Biophysics, Adriano Buzzati-Traverso", National Research Council, Naples, Italy
| | | | - Federica Carrillo
- Institute of Genetics and Biophysics, Adriano Buzzati-Traverso", National Research Council, Naples, Italy
| | | | | | | | - Viola Volpato
- Dementia Research Institute, Cardiff University, Cardiff, UK
| | | | | | | | - Ferdinando Nicoletti
- IRCCS INM Neuromed, Pozzilli, IS, Italy.,Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Caleb Webber
- Dementia Research Institute, Cardiff University, Cardiff, UK.,Oxford Parkinson's Disease Centre, Department of Physiology, Anatomy, Genetics, University of Oxford, Oxford, UK
| | - Antonio Simeone
- Institute of Genetics and Biophysics, Adriano Buzzati-Traverso", National Research Council, Naples, Italy
| | - Sergio Fucile
- IRCCS INM Neuromed, Pozzilli, IS, Italy.,Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | | | - Teresa Esposito
- IRCCS INM Neuromed, Pozzilli, IS, Italy. .,Institute of Genetics and Biophysics, Adriano Buzzati-Traverso", National Research Council, Naples, Italy.
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11
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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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12
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Abstract
Lysosomes are acidic membrane-bound organelles that use hydrolytic enzymes to break down material through pathways such as endocytosis, phagocytosis, mitophagy, and autophagy. To function properly, intralysosomal environments are strictly controlled by a set of integral membrane proteins such as ion channels and transporters. Potassium ion (K+) channels are a large and diverse family of membrane proteins that control K+ flux across both the plasma membrane and intracellular membranes. In the plasma membrane, they are essential in both excitable and non-excitable cells for the control of membrane potential and cell signaling. However, our understanding of intracellular K+ channels is very limited. In this review, we summarize the recent development in studies of K+ channels in the lysosome. We focus on their characterization, potential roles in maintaining lysosomal membrane potential and lysosomal function, and pathological implications.
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Affiliation(s)
- Peng Huang
- Collaborative Innovation Center for Biomedicine, School of Clinical Medicine, Shanghai University of Medicine and Health Sciences, Shanghai, China
| | - Mengnan Xu
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, Halifax, NS, Canada
| | - Yi Wu
- Collaborative Innovation Center for Biomedicine, School of Clinical Medicine, Shanghai University of Medicine and Health Sciences, Shanghai, China
| | - Alia Kazim Rizvi Syeda
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, Halifax, NS, Canada
| | - Xian-Ping Dong
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, Halifax, NS, Canada.
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13
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Qu L, Lin B, Zeng W, Fan C, Wu H, Ge Y, Li Q, Li C, Wei Y, Xin J, Wang X, Liu D, Cang C. Lysosomal K + channel TMEM175 promotes apoptosis and aggravates symptoms of Parkinson's disease. EMBO Rep 2022; 23:e53234. [PMID: 35913019 PMCID: PMC9442313 DOI: 10.15252/embr.202153234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/04/2022] [Accepted: 06/13/2022] [Indexed: 11/09/2022] Open
Abstract
Lysosomes are degradative organelles and play vital roles in a variety of cellular processes. Ion channels on the lysosomal membrane are key regulators of lysosomal function. TMEM175 has been identified as a lysosomal potassium channel, but its modulation and physiological functions remain unclear. Here, we show that the apoptotic regulator Bcl-2 binds to and inhibits TMEM175 activity. Accordingly, Bcl-2 inhibitors activate the channel in a caspase-independent way. Increased TMEM175 function inhibits mitophagy, disrupts mitochondrial homeostasis, and increases production of reactive oxygen species (ROS). ROS further activates TMEM175 and thus forms a positive feedback loop to augment apoptosis. In a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease (PD), knockout (KO) of TMEM175 mitigated motor impairment and dopaminergic (DA) neuron loss, suggesting that TMEM175-mediated apoptosis plays an important role in Parkinson's disease (PD). Overall, our study reveals that TMEM175 is an important regulatory site in the apoptotic signaling pathway and a potential therapeutic target for Parkinson's disease (PD).
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Affiliation(s)
- Lili Qu
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei, China
| | - Bingqian Lin
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei, China
| | - Wenping Zeng
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei, China
| | - Chunhong Fan
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei, China
| | - Haotian Wu
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei, China
| | - Yushu Ge
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Qianqian Li
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei, China
| | - Canjun Li
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei, China
| | - Yanan Wei
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei, China
| | - Jing Xin
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xingbing Wang
- Department of Hematology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Dan Liu
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Chunlei Cang
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei, China
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14
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Wu Y, Xu M, Wang P, Syeda AKR, Huang P, Dong XP. Lysosomal potassium channels. Cell Calcium 2022; 102:102536. [PMID: 35016151 DOI: 10.1016/j.ceca.2022.102536] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 12/21/2022]
Abstract
The lysosome is an important membrane-bound acidic organelle that is regarded as the degradative center as well as multifunctional signaling hub. It digests unwanted macromolecules, damaged organelles, microbes, and other materials derived from endocytosis, autophagy, and phagocytosis. To function properly, the ionic homeostasis and membrane potential of the lysosome are strictly regulated by transporters and ion channels. As the most abundant cation inside the cell, potassium ions (K+) are vital for lysosomal membrane potential and lysosomal calcium (Ca2+) signaling. However, our understanding about how lysosomal K+homeostasis is regulated and what are the functions of K+in the lysosome is very limited. Currently, two lysosomal K+channels have been identified: large-conductance Ca2+-activated K+channel (BK) and transmembrane Protein 175 (TMEM175). In this review, we summarize recent development in our understanding of K+ homeostasis and K+channels in the lysosome. We hope to guide the readers into a more in-depth discussion of lysosomal K+ channels in lysosomal physiology and human diseases.
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Affiliation(s)
- Yi Wu
- Collaborative Innovation Center for Biomedicine, Shanghai University of Medicine and Health Sciences, 279 Zhouzhu Rd, Shanghai 201318, China; School of Pharmacy, Shanghai University of Medicine and Health Sciences, 279 Zhouzhu Rd, Shanghai 201318, China
| | - Mengnan Xu
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova NS B3H 4R2, Canada
| | - Pingping Wang
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova NS B3H 4R2, Canada
| | - Alia Kazim Rizvi Syeda
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova NS B3H 4R2, Canada
| | - Peng Huang
- Collaborative Innovation Center for Biomedicine, Shanghai University of Medicine and Health Sciences, 279 Zhouzhu Rd, Shanghai 201318, China; School of Clinical Medicine, Shanghai University of Medicine and Health Sciences, 279 Zhouzhu Rd, Shanghai 201318, China.
| | - Xian-Ping Dong
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova NS B3H 4R2, Canada.
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15
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Abstract
Lysosomes offer a unique arrangement of degradative, exocytic, and signaling capabilities that make their continued function critical to cellular homeostasis. Lysosomes owe their function to the activity of lysosomal ion channels and transporters, which maintain concentration gradients of H+, K+, Ca2+, Na+, and Cl- across the lysosomal membrane. This review examines the contributions of lysosomal ion channels to lysosome function, showing how ion channel function is integral to degradation and autophagy, maintaining lysosomal membrane potential, controlling Ca2+ signaling, and facilitating exocytosis. Evidence of lysosome dysfunction in a variety of disease pathologies creates a need to understand how lysosomal ion channels contribute to lysosome dysfunction. For example, the loss of function of the TRPML1 Ca2+ lysosome channel in multiple lysosome storage diseases leads to lysosome dysfunction and disease pathogenesis while neurodegenerative diseases are marked by lysosome dysfunction caused by changes in ion channel activity through the TRPML1, TPC, and TMEM175 ion channels. Autoimmune disease is marked by dysregulated autophagy, which is dependent on the function of multiple lysosomal ion channels. Understanding the role of lysosomal ion channel activity in lysosome membrane permeability and NLRP3 inflammasome activation could provide valuable mechanistic insight into NLRP3 inflammasome-mediated diseases. Finally, this review seeks to show that understanding the role of lysosomal ion channels in lysosome dysfunction could give mechanistic insight into the efficacy of certain drug classes, specifically those that target the lysosome, such as cationic amphiphilic drugs.
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Affiliation(s)
- Rebekah L Kendall
- Department of Biomedical and Pharmaceutical Sciences, Center for Environmental Health Sciences, University of Montana, Missoula, MT, USA
| | - Andrij Holian
- Department of Biomedical and Pharmaceutical Sciences, Center for Environmental Health Sciences, University of Montana, Missoula, MT, USA
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16
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Zhang M, Lu H, Xie X, Shen H, Li X, Zhang Y, Wu J, Ni J, Li H, Chen G. TMEM175 mediates Lysosomal function and participates in neuronal injury induced by cerebral ischemia-reperfusion. Mol Brain 2020; 13:113. [PMID: 32799888 PMCID: PMC7429711 DOI: 10.1186/s13041-020-00651-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 08/03/2020] [Indexed: 01/15/2023] Open
Abstract
As the main organelles for the clearance of damaged proteins and damaged organelles, the function of lysosomes is crucial for maintaining the intracellular homeostasis of long-lived neurons. A stable acidic environment is essential for lysosomes to perform their functions. TMEM175 has been identified as a new K+ channel that is responsible for regulating lysosomal membrane potential and pH stability in neurons. This study aimed to understand the role of TMEM175 in lysosomal function of neurons and neuronal injury following cerebral ischemia-reperfusion (I/R). A middle-cerebral-artery occlusion/reperfusion (MCAO/R) model was established in adult male Sprague-Dawley rats in vivo, and cultured neurons were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) to mimic ischemia-reperfusion (I/R) injury in vitro. We found that the protein level of TMEM175 decreased after cerebral I/R injury and that TMEM175 overexpression ameliorated MCAO/R-induced brain-cell death and neurobehavioral deficits in vivo. Furthermore, these results were recapitulated in cultured neurons. Acridine orange (AO) staining, as well as LysoSensor Green DND-189, cathepsin-B (CTSB), and cathepsin-D (CTSD) activities, showed that TMEM175 deficiency inhibited the hydrolytic function of lysosomes by affecting lysosomal pH. In contrast, TMEM175 upregulation reversed OGD/R-induced lysosomal dysfunction and impaired mitochondrial accumulation in cultured neurons. TMEM175 deficiency induced by cerebral I/R injury leads to compromised lysosomal pH stability, thus inhibiting the hydrolytic function of lysosomes. Consequently, lysosomal-dependent degradation of damaged mitochondria is suppressed and thereby exacerbates brain damage. Exogenous up-regulation of TMEM175 protein level could reverse the neuronal lysosomal dysfunction after ischemia-reperfusion.
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Affiliation(s)
- Mengling Zhang
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Haifeng Lu
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Xueshun Xie
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Haitao Shen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Xiang Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Yunhai Zhang
- Jiangsu Key Laboratory of Medical Optics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Jiang Wu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Jianqiang Ni
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China.
| | - Haiying Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China.
| | - Gang Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
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17
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Hopfner F, Mueller SH, Szymczak S, Junge O, Tittmann L, May S, Lohmann K, Grallert H, Lieb W, Strauch K, Müller-Nurasyid M, Berger K, Schormair B, Winkelmann J, Mollenhauer B, Trenkwalder C, Maetzler W, Berg D, Kasten M, Klein C, Höglinger GU, Gasser T, Deuschl G, Franke A, Krawczak M, Dempfle A, Kuhlenbäumer G. Rare Variants in Specific Lysosomal Genes Are Associated With Parkinson's Disease. Mov Disord 2020; 35:1245-1248. [PMID: 32267580 DOI: 10.1002/mds.28037] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/02/2020] [Accepted: 03/09/2020] [Indexed: 02/02/2023] Open
Abstract
OBJECTIVE Impaired lysosomal degradation of α-synuclein and other cellular constituents may play an important role in Parkinson's disease (PD). Rare genetic variants in the glucocerebrosidase (GBA) gene were consistently associated with PD. Here we examine the association between rare variants in lysosomal candidate genes and PD. METHODS We investigated the association between PD and rare genetic variants in 23 lysosomal candidate genes in 4096 patients with PD and an equal number of controls using pooled targeted next-generation DNA sequencing. Genewise association of rare variants in cases or controls was analyzed using the optimized sequence kernel association test with Bonferroni correction for the 23 tested genes. RESULTS We confirm the association of rare variants in GBA with PD and report novel associations for rare variants in ATP13A2, LAMP1, TMEM175, and VPS13C. CONCLUSION Rare variants in selected lysosomal genes, first and foremost GBA, are associated with PD. Rare variants in ATP13A2 and VPC13C previously linked to monogenic PD and more common variants in TMEM175 and VPS13C previously linked to sporadic PD in genome-wide association studies are associated with PD. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Franziska Hopfner
- Department of Neurology, Universitätsklinikum Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany.,Department of Neurology, Hannover Medical School, Hannover, Germany
| | - Stefanie H Mueller
- Department of Neurology, Universitätsklinikum Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany.,Institute of Health Informatics, University College London, London, United Kingdom
| | - Silke Szymczak
- Institute of Medical Informatics and Statistics, Kiel University, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Olaf Junge
- Institute of Medical Informatics and Statistics, Kiel University, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Lukas Tittmann
- Institute of Epidemiology, University of Kiel, Kiel, Germany
| | - Sandra May
- Institute of Clinical Molecular Biology, Kiel University, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Katja Lohmann
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Harald Grallert
- Institute of Epidemiology II, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany.,Research Unit of Molecular Epidemiology, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany.,German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany
| | - Wolfgang Lieb
- Institute of Epidemiology, University of Kiel, Kiel, Germany
| | - Konstantin Strauch
- Institute of Genetic Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany.,Institute of Medical Informatics, Biometry and Epidemiology, Ludwig-Maximilians-University, Munich, Germany
| | - Martina Müller-Nurasyid
- Institute of Genetic Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany.,Department of Medicine I, Ludwig-Maximilians-Universität, Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Munich Heart Alliance, Munich, Germany
| | - Klaus Berger
- Institute of Epidemiology and Social Medicine, University of Münster, Münster, Germany
| | - Barbara Schormair
- Institute of Neurogenomics, Helmholtz Zentrum München GmbH, German Research Center for Environmental Health, Neuherberg, Germany
| | - Juliane Winkelmann
- Institute of Neurogenomics, Helmholtz Zentrum München GmbH, German Research Center for Environmental Health, Neuherberg, Germany.,Institute of Human Genetics, Faculty of Medicine, Technical University Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), München, Deutschland
| | - Brit Mollenhauer
- Paracelsus-Elena-Klinik Kassel, Kassel, Germany.,Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Claudia Trenkwalder
- Clinic for Neurosurgery, University Medical Centre, Georg August University Göttingen, Göttingen, Germany.,Paracelsus-Elena Hospital, Kassel, Germany
| | - Walter Maetzler
- Department of Neurology, Universitätsklinikum Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
| | - Daniela Berg
- Department of Neurology, Universitätsklinikum Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
| | - Meike Kasten
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany.,Department of Psychiatry and Psychotherapy, University of Lübeck, Lübeck, Germany
| | - Christine Klein
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Günter U Höglinger
- Technical University of Munich, School of Medicine, Department of Neurology, Munich, Germany.,German Center for Neurodegenerative Diseases, Munich, Germany.,Department of Neurology, Hannover Medical School, Hannover, Germany
| | - Thomas Gasser
- Hertie Institute for Clinical Brain Research and German Center for Neurodegenerative Diseases, University Clinic Tuebingen, Tuebingen, Germany
| | - Günther Deuschl
- Department of Neurology, Universitätsklinikum Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
| | - André Franke
- Institute of Clinical Molecular Biology, Kiel University, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Michael Krawczak
- Institute of Medical Informatics and Statistics, Kiel University, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Astrid Dempfle
- Institute of Medical Informatics and Statistics, Kiel University, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Gregor Kuhlenbäumer
- Department of Neurology, Universitätsklinikum Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
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18
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Feng X, Zhao Z, Li Q, Tan Z. Lysosomal Potassium Channels: Potential Roles in Lysosomal Function and Neurodegenerative Diseases. CNS Neurol Disord Drug Targets 2019; 17:261-266. [PMID: 29422008 DOI: 10.2174/1871527317666180202110717] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 11/14/2017] [Accepted: 12/25/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND & OBJECTIVE The lysosome is a membrane-enclosed organelle widely found in every eukaryotic cell. It has been deemed as the stomach of the cells. Recent studies revealed that it also functions as an intracellular calcium store and is a platform for nutrient-dependent signal transduction. Similar with the plasma membrane, the lysosome membrane is furnished with various proteins, including pumps, ion channels and transporters. So far, two types of lysosomal potassium channels have been identified: large-conductance and Ca2+-activated potassium channel (BK) and TMEM175. TMEM175 has been linked to several neurodegeneration diseases, such as the Alzheimer and Parkinson disease. Recent studies showed that TMEM175 is a lysosomal potassium channel with novel architecture and plays important roles in setting the lysosomal membrane potential and maintaining pH stability. TMEM175 deficiency leads to compromised lysosomal function, which might be responsible for the pathogenesis of related diseases. BK is a well-known potassium channel for its function on the plasma membrane. Studies from two independent groups revealed that functional BK channels are also expressed on the lysosomal plasma membrane. Dysfunction of BK causes impaired lysosomal calcium signaling and abnormal lipid accumulation, a featured phenotype of most lysosomal storage diseases (LSDs). Boosting BK activity could rescue the lipid accumulation in several LSD cell models. Overall, the lysosomal potassium channels are essential for the lysosome physiological function, including lysosomal calcium signaling and autophagy. The dysfunction of lysosomal potassium channels is related to some neurodegeneration disorders. CONCLUSION Therefore, lysosomal potassium channels are suggested as potential targets for the intervention of lysosomal disorders.
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Affiliation(s)
- Xinghua Feng
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
| | - Zhuangzhuang Zhao
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
| | - Qian Li
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
| | - Zhiyong Tan
- Department of Pharmacology and Toxicology and Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, United States
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Blauwendraat C, Heilbron K, Vallerga CL, Bandres-Ciga S, von Coelln R, Pihlstrøm L, Simón-Sánchez J, Schulte C, Sharma M, Krohn L, Siitonen A, Iwaki H, Leonard H, Noyce AJ, Tan M, Gibbs JR, Hernandez DG, Scholz SW, Jankovic J, Shulman LM, Lesage S, Corvol JC, Brice A, van Hilten JJ, Marinus J, Tienari P, Majamaa K, Toft M, Grosset DG, Gasser T, Heutink P, Shulman JM, Wood N, Hardy J, Morris HR, Hinds DA, Gratten J, Visscher PM, Gan-Or Z, Nalls MA, Singleton AB. Parkinson's disease age at onset genome-wide association study: Defining heritability, genetic loci, and α-synuclein mechanisms. Mov Disord 2019; 34:866-875. [PMID: 30957308 PMCID: PMC6579628 DOI: 10.1002/mds.27659] [Citation(s) in RCA: 196] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/02/2019] [Accepted: 01/21/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Increasing evidence supports an extensive and complex genetic contribution to PD. Previous genome-wide association studies (GWAS) have shed light on the genetic basis of risk for this disease. However, the genetic determinants of PD age at onset are largely unknown. OBJECTIVES To identify the genetic determinants of PD age at onset. METHODS Using genetic data of 28,568 PD cases, we performed a genome-wide association study based on PD age at onset. RESULTS We estimated that the heritability of PD age at onset attributed to common genetic variation was ∼0.11, lower than the overall heritability of risk for PD (∼0.27), likely, in part, because of the subjective nature of this measure. We found two genome-wide significant association signals, one at SNCA and the other a protein-coding variant in TMEM175, both of which are known PD risk loci and a Bonferroni-corrected significant effect at other known PD risk loci, GBA, INPP5F/BAG3, FAM47E/SCARB2, and MCCC1. Notably, SNCA, TMEM175, SCARB2, BAG3, and GBA have all been shown to be implicated in α-synuclein aggregation pathways. Remarkably, other well-established PD risk loci, such as GCH1 and MAPT, did not show a significant effect on age at onset of PD. CONCLUSIONS Overall, we have performed the largest age at onset of PD genome-wide association studies to date, and our results show that not all PD risk loci influence age at onset with significant differences between risk alleles for age at onset. This provides a compelling picture, both within the context of functional characterization of disease-linked genetic variability and in defining differences between risk alleles for age at onset, or frank risk for disease. © 2019 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Cornelis Blauwendraat
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
- Neurodegenerative Diseases Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Karl Heilbron
- 23andMe, Inc., 899 W Evelyn Avenue, Mountain View, CA, USA
| | - Costanza L. Vallerga
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Sara Bandres-Ciga
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Rainer von Coelln
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Lasse Pihlstrøm
- Department of Neurology, Oslo University Hospital, Oslo, Norway
| | - Javier Simón-Sánchez
- Department for Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Claudia Schulte
- Department for Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Manu Sharma
- Centre for Genetic Epidemiology, Institute for Clinical Epidemiology and Applied Biometry, University of Tubingen, Germany
| | - Lynne Krohn
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Ari Siitonen
- Institute of Clinical Medicine, Department of Neurology, University of Oulu, Oulu, Finland
- Department of Neurology and Medical Research Center, Oulu University Hospital, Oulu, Finland
| | - Hirotaka Iwaki
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
- The Michael J Fox Foundation for Parkinson’s Research, NY, USA
| | - Hampton Leonard
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Alastair J. Noyce
- Preventive Neurology Unit, Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Manuela Tan
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - J. Raphael Gibbs
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Dena G. Hernandez
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Sonja W. Scholz
- Neurodegenerative Diseases Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Joseph Jankovic
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Lisa M. Shulman
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Suzanne Lesage
- Inserm U1127, Sorbonne Universités, UPMC Univ Paris 06 UMR S1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Jean-Christophe Corvol
- Inserm U1127, Sorbonne Universités, UPMC Univ Paris 06 UMR S1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Alexis Brice
- Inserm U1127, Sorbonne Universités, UPMC Univ Paris 06 UMR S1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | | | - Johan Marinus
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Pentti Tienari
- Institute of Clinical Medicine, Department of Neurology, University of Oulu, Oulu, Finland
- Department of Neurology and Medical Research Center, Oulu University Hospital, Oulu, Finland
| | - Kari Majamaa
- Institute of Clinical Medicine, Department of Neurology, University of Oulu, Oulu, Finland
- Department of Neurology and Medical Research Center, Oulu University Hospital, Oulu, Finland
| | - Mathias Toft
- Department of Neurology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Donald G. Grosset
- Department of Neurology, Institute of Neurological Sciences, Queen Elizabeth University Hospital, Glasgow, UK
- Institute of Neuroscience & Psychology, University of Glasgow, Glasgow, UK
| | - Thomas Gasser
- Department for Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Peter Heutink
- Department for Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Joshua M Shulman
- Departments of Molecular & Human Genetics and Neuroscience, Baylor College of Medicine, Houston, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, USA
| | - Nicolas Wood
- Inserm U1127, Sorbonne Universités, UPMC Univ Paris 06 UMR S1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - John Hardy
- Inserm U1127, Sorbonne Universités, UPMC Univ Paris 06 UMR S1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Huw R Morris
- Department of Clinical Neuroscience, UCL Institute of Neurology, London UK
- UCL Movement Disorders Centre, UCL Institute of Neurology, London, UK
| | - David A. Hinds
- 23andMe, Inc., 899 W Evelyn Avenue, Mountain View, CA, USA
| | - Jacob Gratten
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Peter M. Visscher
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Ziv Gan-Or
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
- Department of Neurology & Neurosurgery, McGill University, Montreal, Quebec, Canada
| | - Mike A. Nalls
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
- Data Tecnica International, Glen Echo, MD, USA
| | - Andrew B. Singleton
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
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Sterea AM, Almasi S, El Hiani Y. The hidden potential of lysosomal ion channels: A new era of oncogenes. Cell Calcium 2018; 72:91-103. [PMID: 29748137 DOI: 10.1016/j.ceca.2018.02.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 02/28/2018] [Accepted: 02/28/2018] [Indexed: 01/14/2023]
Abstract
Lysosomes serve as the control centre for cellular clearance. These membrane-bound organelles receive biomolecules destined for degradation from intracellular and extracellular pathways; thus, facilitating the production of energy and shaping the fate of the cell. At the base of their functionality are the lysosomal ion channels which mediate the function of the lysosome through the modulation of ion influx and efflux. Ion channels form pores in the membrane of lysosomes and allow the passage of ions, a seemingly simple task which harbours the potential of overthrowing the cell's stability. Considered the master regulators of ion homeostasis, these integral membrane proteins enable the proper operation of the lysosome. Defects in the structure or function of these ion channels lead to the development of lysosomal storage diseases, neurodegenerative diseases and cancer. Although more than 50 years have passed since their discovery, lysosomes are not yet fully understood, with their ion channels being even less well characterized. However, significant improvements have been made in the development of drugs targeted against these ion channels as a means of combating diseases. In this review, we will examine how Ca2+, K+, Na+ and Cl- ion channels affect the function of the lysosome, their involvement in hereditary and spontaneous diseases, and current ion channel-based therapies.
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Affiliation(s)
- Andra M Sterea
- Departments of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Shekoufeh Almasi
- Departments of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Yassine El Hiani
- Departments of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.
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Jinn S, Drolet RE, Cramer PE, Wong AH, Toolan DM, Gretzula CA, Voleti B, Vassileva G, Disa J, Tadin-Strapps M, Stone DJ. TMEM175 deficiency impairs lysosomal and mitochondrial function and increases α-synuclein aggregation. Proc Natl Acad Sci U S A 2017; 114:2389-94. [PMID: 28193887 DOI: 10.1073/pnas.1616332114] [Citation(s) in RCA: 138] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Parkinson disease (PD) is a neurodegenerative disorder pathologically characterized by nigrostriatal dopamine neuron loss and the postmortem presence of Lewy bodies, depositions of insoluble α-synuclein, and other proteins that likely contribute to cellular toxicity and death during the disease. Genetic and biochemical studies have implicated impaired lysosomal and mitochondrial function in the pathogenesis of PD. Transmembrane protein 175 (TMEM175), the lysosomal K+ channel, is centered under a major genome-wide association studies peak for PD, making it a potential candidate risk factor for the disease. To address the possibility that variation in TMEM175 could play a role in PD pathogenesis, TMEM175 function was investigated in a neuronal model system. Studies confirmed that TMEM175 deficiency results in unstable lysosomal pH, which led to decreased lysosomal catalytic activity, decreased glucocerebrosidase activity, impaired autophagosome clearance by the lysosome, and decreased mitochondrial respiration. Moreover, TMEM175 deficiency in rat primary neurons resulted in increased susceptibility to exogenous α-synuclein fibrils. Following α-synuclein fibril treatment, neurons deficient in TMEM175 were found to have increased phosphorylated and detergent-insoluble α-synuclein deposits. Taken together, data from these studies suggest that TMEM175 plays a direct and critical role in lysosomal and mitochondrial function and PD pathogenesis and highlight this ion channel as a potential therapeutic target for treating PD.
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