1
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Feng T, Zheng H, Zhang Z, Fan P, Yang X. Mechanism and therapeutic targets of the involvement of a novel lysosomal proton channel TMEM175 in Parkinson's disease. Ageing Res Rev 2024; 100:102373. [PMID: 38960046 DOI: 10.1016/j.arr.2024.102373] [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: 02/11/2024] [Revised: 06/01/2024] [Accepted: 06/04/2024] [Indexed: 07/05/2024]
Abstract
Parkinson's disease (PD), recognized as the second most prevalent neurodegenerative disease in the aging population, presents a significant challenge due to the current lack of effective treatment methods to mitigate its progression. Many pathogenesis of PD are related to lysosomal dysfunction. Moreover, extensive genetic studies have shown a significant correlation between the lysosomal membrane protein TMEM175 and the risk of developing PD. Building on this discovery, TMEM175 has been identified as a novel potassium ion channel. Intriguingly, further investigations have found that potassium ion channels gradually close and transform into hydrion "excretion" channels in the microenvironment of lysosomes. This finding was further substantiated by studies on TMEM175 knockout mice, which exhibited pronounced motor dysfunction in pole climbing and suspension tests, alongside a notable reduction in dopamine neurons within the substantia nigra compacta. Despite these advancements, the current research landscape is not without its controversies. In light of this, the present review endeavors to methodically examine and consolidate a vast array of recent literature on TMEM175. This comprehensive analysis spans from the foundational research on the structure and function of TMEM175 to expansive population genetics studies and mechanism research utilizing cellular and animal models.A thorough understanding of the structure and function of TMEM175, coupled with insights into the intricate mechanisms underpinning lysosomal dysfunction in PD dopaminergic neurons, is imperative. Such knowledge is crucial for pinpointing precise intervention targets, thereby paving the way for novel therapeutic strategies that could potentially alter the neurodegenerative trajectory of PD.
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Affiliation(s)
- Tingting Feng
- Department of Neurology, Second Affiliated Hospital of Xinjiang Medical University, Urumqi 830063, China; Xinjiang Key Laboratory of Nervous System Disease Research, Urumqi 830063,China; Xinjiang Clinical Research Center for Nervous System Diseases, Urumqi 830063, China; Xinjiang Medical University, Urumqi 830017, China
| | | | - Zhan Zhang
- Department of Neurology, Second Affiliated Hospital of Xinjiang Medical University, Urumqi 830063, China; Xinjiang Key Laboratory of Nervous System Disease Research, Urumqi 830063,China; Xinjiang Clinical Research Center for Nervous System Diseases, Urumqi 830063, China
| | - Peidong Fan
- Department of Neurology, Second Affiliated Hospital of Xinjiang Medical University, Urumqi 830063, China; Xinjiang Key Laboratory of Nervous System Disease Research, Urumqi 830063,China; Xinjiang Clinical Research Center for Nervous System Diseases, Urumqi 830063, China
| | - Xinling Yang
- Department of Neurology, Second Affiliated Hospital of Xinjiang Medical University, Urumqi 830063, China; Xinjiang Key Laboratory of Nervous System Disease Research, Urumqi 830063,China; Xinjiang Clinical Research Center for Nervous System Diseases, Urumqi 830063, China; Xinjiang Medical University, Urumqi 830017, China.
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2
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Wu Y, Huang J, Zhang F, Guivel-Benhassine F, Hubert M, Schwartz O, Xiao W, Cintrat JC, Qu L, Barbier J, Gillet D, Cang C. Endolysosomal channel TMEM175 mediates antitoxin activity of DABMA. FEBS J 2024; 291:4142-4154. [PMID: 39097908 DOI: 10.1111/febs.17242] [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: 11/12/2023] [Revised: 02/21/2024] [Accepted: 07/24/2024] [Indexed: 08/06/2024]
Abstract
DABMA is a chemical molecule optimized from the parent compound ABMA and exhibits broad-spectrum antipathogenic activity by modulating the host's endolysosomal and autophagic pathways. Both DABMA and ABMA inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a cellular assay, which further expands their anti-pathogen spectrum in vitro. However, their precise mechanism of action has not yet been resolved. TMEM175 is a newly characterized endolysosomal channel which plays an essential role in the homeostasis of endosomes and lysosomes as well as organelle fusion. Here, we show that DABMA increases the endosomal TMEM175 current through organelle patch clamping with an EC50 of 17.9 μm. Depletion of TMEM175 protein significantly decreases the antitoxin activity of DABMA and affects its action on acidic- and Rab7-positive endosomes as well as on endolysosomal trafficking. Thus, TMEM175 is necessary for DABMA's activity and may represent a druggable target for the development of anti-infective drugs. Moreover, DABMA, as an activator of the TMEM175 channel, may be useful for the in-depth characterization of the physiological and pathological roles of this endolysosomal channel.
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Affiliation(s)
- Yu Wu
- Institute of Health and Medicine, Hefei Comprehensive National Science Center, China
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé, SIMoS, Gif-sur-Yvette, France
| | - Jiamin Huang
- The CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei, China
| | - Fei Zhang
- The CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei, China
| | | | - Mathieu Hubert
- Unité virus et immunité, Département de Virologie, Institut Pasteur, Paris, France
| | - Olivier Schwartz
- Unité virus et immunité, Département de Virologie, Institut Pasteur, Paris, France
| | - Weihua Xiao
- The CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei, China
| | - Jean-Christophe Cintrat
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé, SCBM, Gif-sur-Yvette, France
| | - Lili Qu
- The CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei, China
| | - Julien Barbier
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé, SIMoS, Gif-sur-Yvette, France
| | - Daniel Gillet
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé, SIMoS, Gif-sur-Yvette, France
| | - Chunlei Cang
- Institute of Health and Medicine, Hefei Comprehensive National Science Center, China
- The CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei, China
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3
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Oh S, Lee J, Choi HJ, Kim S, Sapuru V, Kim M, Hite RK. Discovery of Selective Inhibitors for the Lysosomal Parkinson's Disease Channel TMEM175. J Am Chem Soc 2024; 146:23230-23239. [PMID: 39116214 DOI: 10.1021/jacs.4c05623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
TMEM175 is a lysosomal potassium and proton channel that is associated with the development of Parkinson's disease. Advances in understanding the physiological roles of TMEM175 have been hampered by the absence of selective inhibitors, and studies involving genetic perturbations have yielded conflicting results. Here, we report the discovery and characterization of the first reported TMEM175-selective inhibitors, 2-phenylpyridin-4-ylamine (2-PPA), and AP-6. Cryo-EM structures of human TMEM175 bound by 2-PPA and AP-6 reveal that they act as pore blockers, binding at distinct sites in the pore and occluding the ion permeation pathway. Acute inhibition of TMEM175 by 2-PPA or AP-6 increases the level of lysosomal macromolecule catabolism, thereby accelerating macropinocytosis and other digestive processes. These inhibitors may serve as valuable tools to study the roles of TMEM175 in regulating lysosomal function and provide useful templates for future therapeutic development in Parkinson's disease.
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Affiliation(s)
- SeCheol Oh
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Jooyeon Lee
- Department of Chemistry, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Ho Jeong Choi
- Department of Chemistry, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Songwon Kim
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Vinay Sapuru
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
- Physiology, Biophysics, and Systems Biology (PBSB) Program, Weill Cornell Graduate School of Biomedical Sciences, 1300 York Avenue, New York, New York 10065, United States
| | - Min Kim
- Department of Chemistry, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Richard K Hite
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
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4
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Nixon RA, Rubinsztein DC. Mechanisms of autophagy-lysosome dysfunction in neurodegenerative diseases. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00757-5. [PMID: 39107446 DOI: 10.1038/s41580-024-00757-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2024] [Indexed: 08/15/2024]
Abstract
Autophagy is a lysosome-based degradative process used to recycle obsolete cellular constituents and eliminate damaged organelles and aggregate-prone proteins. Their postmitotic nature and extremely polarized morphologies make neurons particularly vulnerable to disruptions caused by autophagy-lysosomal defects, especially as the brain ages. Consequently, mutations in genes regulating autophagy and lysosomal functions cause a wide range of neurodegenerative diseases. Here, we review the role of autophagy and lysosomes in neurodegenerative diseases such as Alzheimer disease, Parkinson disease and frontotemporal dementia. We also consider the strong impact of cellular ageing on lysosomes and autophagy as a tipping point for the late-age emergence of related neurodegenerative disorders. Many of these diseases have primary defects in autophagy, for example affecting autophagosome formation, and in lysosomal functions, especially pH regulation and calcium homeostasis. We have aimed to provide an integrative framework for understanding the central importance of autophagic-lysosomal function in neuronal health and disease.
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Affiliation(s)
- Ralph A Nixon
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York, NY, USA.
- Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, USA.
- Department of Cell Biology, New York University Grossman School of Medicine, New York, NY, USA.
- Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA.
| | - David C Rubinsztein
- Department of Medical Genetics, Cambridge Institute for Medical Research, Cambridge, UK
- UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, UK
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5
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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 PMCID: PMC11381013 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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6
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Kang H, Lee CJ. Transmembrane proteins with unknown function (TMEMs) as ion channels: electrophysiological properties, structure, and pathophysiological roles. Exp Mol Med 2024; 56:850-860. [PMID: 38556553 PMCID: PMC11059273 DOI: 10.1038/s12276-024-01206-1] [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: 07/06/2023] [Revised: 12/27/2023] [Accepted: 01/19/2024] [Indexed: 04/02/2024] Open
Abstract
A transmembrane (TMEM) protein with an unknown function is a type of membrane-spanning protein expressed in the plasma membrane or the membranes of intracellular organelles. Recently, several TMEM proteins have been identified as functional ion channels. The structures and functions of these proteins have been extensively studied over the last two decades, starting with TMEM16A (ANO1). In this review, we provide a summary of the electrophysiological properties of known TMEM proteins that function as ion channels, such as TMEM175 (KEL), TMEM206 (PAC), TMEM38 (TRIC), TMEM87A (GolpHCat), TMEM120A (TACAN), TMEM63 (OSCA), TMEM150C (Tentonin3), and TMEM43 (Gapjinc). Additionally, we examine the unique structural features of these channels compared to those of other well-known ion channels. Furthermore, we discuss the diverse physiological roles of these proteins in lysosomal/endosomal/Golgi pH regulation, intracellular Ca2+ regulation, spatial memory, cell migration, adipocyte differentiation, and mechanical pain, as well as their pathophysiological roles in Parkinson's disease, cancer, osteogenesis imperfecta, infantile hypomyelination, cardiomyopathy, and auditory neuropathy spectrum disorder. This review highlights the potential for the discovery of novel ion channels within the TMEM protein family and the development of new therapeutic targets for related channelopathies.
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Affiliation(s)
- Hyunji Kang
- Center for Cognition and Sociality, Life Science Cluster, Institute for Basic Science (IBS), 55 Expo-ro, Yuseong-gu, Daejeon, 34126, Republic of Korea
| | - C Justin Lee
- Center for Cognition and Sociality, Life Science Cluster, Institute for Basic Science (IBS), 55 Expo-ro, Yuseong-gu, Daejeon, 34126, Republic of Korea.
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7
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Settembre C, Perera RM. Lysosomes as coordinators of cellular catabolism, metabolic signalling and organ physiology. Nat Rev Mol Cell Biol 2024; 25:223-245. [PMID: 38001393 DOI: 10.1038/s41580-023-00676-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2023] [Indexed: 11/26/2023]
Abstract
Every cell must satisfy basic requirements for nutrient sensing, utilization and recycling through macromolecular breakdown to coordinate programmes for growth, repair and stress adaptation. The lysosome orchestrates these key functions through the synchronised interplay between hydrolytic enzymes, nutrient transporters and signalling factors, which together enable metabolic coordination with other organelles and regulation of specific gene expression programmes. In this Review, we discuss recent findings on lysosome-dependent signalling pathways, focusing on how the lysosome senses nutrient availability through its physical and functional association with mechanistic target of rapamycin complex 1 (mTORC1) and how, in response, the microphthalmia/transcription factor E (MiT/TFE) transcription factors exert feedback regulation on lysosome biogenesis. We also highlight the emerging interactions of lysosomes with other organelles, which contribute to cellular homeostasis. Lastly, we discuss how lysosome dysfunction contributes to diverse disease pathologies and how inherited mutations that compromise lysosomal hydrolysis, transport or signalling components lead to multi-organ disorders with severe metabolic and neurological impact. A deeper comprehension of lysosomal composition and function, at both the cellular and organismal level, may uncover fundamental insights into human physiology and disease.
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Affiliation(s)
- Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy.
- Department of Clinical Medicine and Surgery, Federico II University, Naples, Italy.
| | - Rushika M Perera
- Department of Anatomy, University of California at San Francisco, San Francisco, CA, USA.
- Department of Pathology, University of California at San Francisco, San Francisco, CA, USA.
- Helen Diller Family Comprehensive Cancer Center, University of California at San Francisco, San Francisco, CA, USA.
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8
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Tan JX, Finkel T. Lysosomes in senescence and aging. EMBO Rep 2023; 24:e57265. [PMID: 37811693 PMCID: PMC10626421 DOI: 10.15252/embr.202357265] [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: 03/29/2023] [Revised: 08/08/2023] [Accepted: 09/21/2023] [Indexed: 10/10/2023] Open
Abstract
Dysfunction of lysosomes, the primary hydrolytic organelles in animal cells, is frequently associated with aging and age-related diseases. At the cellular level, lysosomal dysfunction is strongly linked to cellular senescence or the induction of cell death pathways. However, the precise mechanisms by which lysosomal dysfunction participates in these various cellular or organismal phenotypes have remained elusive. The ability of lysosomes to degrade diverse macromolecules including damaged proteins and organelles puts lysosomes at the center of multiple cellular stress responses. Lysosomal activity is tightly regulated by many coordinated cellular processes including pathways that function inside and outside of the organelle. Here, we collectively classify these coordinated pathways as the lysosomal processing and adaptation system (LYPAS). We review evidence that the LYPAS is upregulated by diverse cellular stresses, its adaptability regulates senescence and cell death decisions, and it can form the basis for therapeutic manipulation for a wide range of age-related diseases and potentially for aging itself.
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Affiliation(s)
- Jay Xiaojun Tan
- Aging InstituteUniversity of Pittsburgh School of Medicine/University of Pittsburgh Medical CenterPittsburghPAUSA
- Department of Cell BiologyUniversity of Pittsburgh School of MedicinePittsburghPAUSA
| | - Toren Finkel
- Aging InstituteUniversity of Pittsburgh School of Medicine/University of Pittsburgh Medical CenterPittsburghPAUSA
- Department of MedicineUniversity of Pittsburgh School of MedicinePittsburghPAUSA
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9
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Zheng W, Rawson S, Shen Z, Tamilselvan E, Smith HE, Halford J, Shen C, Murthy SE, Ulbrich MH, Sotomayor M, Fu TM, Holt JR. TMEM63 proteins function as monomeric high-threshold mechanosensitive ion channels. Neuron 2023; 111:3195-3210.e7. [PMID: 37543036 PMCID: PMC10592209 DOI: 10.1016/j.neuron.2023.07.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 05/12/2023] [Accepted: 07/08/2023] [Indexed: 08/07/2023]
Abstract
OSCA/TMEM63s form mechanically activated (MA) ion channels in plants and animals, respectively. OSCAs and related TMEM16s and transmembrane channel-like (TMC) proteins form homodimers with two pores. Here, we uncover an unanticipated monomeric configuration of TMEM63 proteins. Structures of TMEM63A and TMEM63B (referred to as TMEM63s) revealed a single highly restricted pore. Functional analyses demonstrated that TMEM63s are bona fide mechanosensitive ion channels, characterized by small conductance and high thresholds. TMEM63s possess evolutionary variations in the intracellular linker IL2, which mediates dimerization in OSCAs. Replacement of OSCA1.2 IL2 with TMEM63A IL2 or mutations to key variable residues resulted in monomeric OSCA1.2 and MA currents with significantly higher thresholds. Structural analyses revealed substantial conformational differences in the mechano-sensing domain IL2 and gating helix TM6 between TMEM63s and OSCA1.2. Our studies reveal that mechanosensitivity in OSCA/TMEM63 channels is affected by oligomerization and suggest gating mechanisms that may be shared by OSCA/TMEM63, TMEM16, and TMC channels.
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Affiliation(s)
- Wang Zheng
- Departments of Otolaryngology & Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
| | - Shaun Rawson
- Harvard Cryo-Electron Microscopy Center for Structural Biology, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Zhangfei Shen
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Elakkiya Tamilselvan
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Biophysics Program, The Ohio State University, Columbus, OH 43210, USA
| | - Harper E Smith
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Biophysics Program, The Ohio State University, Columbus, OH 43210, USA
| | - Julia Halford
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Chen Shen
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Swetha E Murthy
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Maximilian H Ulbrich
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany; Internal Medicine IV, University of Freiburg Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Biophysics Program, The Ohio State University, Columbus, OH 43210, USA
| | - Tian-Min Fu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA.
| | - Jeffrey R Holt
- Departments of Otolaryngology & Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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10
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Shi GS, Qin QL, Huang C, Li ZR, Wang ZH, Wang YY, He XY, Zhao XM. The Pathological Mechanism of Neuronal Autophagy-Lysosome Dysfunction After Ischemic Stroke. Cell Mol Neurobiol 2023; 43:3251-3263. [PMID: 37382853 DOI: 10.1007/s10571-023-01382-0] [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: 05/23/2023] [Accepted: 06/22/2023] [Indexed: 06/30/2023]
Abstract
The abnormal initiation of autophagy flux in neurons after ischemic stroke caused dysfunction of autophagy-lysosome, which not only led to autophagy flux blockage, but also resulted in autophagic death of neurons. However, the pathological mechanism of neuronal autophagy-lysosome dysfunction did not form a unified viewpoint until now. In this review, taking the autophagy lysosomal dysfunction of neurons as a starting point, we summarized the molecular mechanisms that led to neuronal autophagy lysosomal dysfunction after ischemic stroke, which would provide theoretical basis for the clinical treatment of ischemic stroke.
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Affiliation(s)
- Guang-Sen Shi
- Faculty of Medicine, Kunming University of Science and Technology, Kunming, 650500, China
| | - Qi-Lin Qin
- Faculty of Medicine, Kunming University of Science and Technology, Kunming, 650500, China
| | - Cheng Huang
- Faculty of Medicine, Kunming University of Science and Technology, Kunming, 650500, China
| | - Zi-Rong Li
- Faculty of Medicine, Kunming University of Science and Technology, Kunming, 650500, China
| | - Zi-Han Wang
- Faculty of Medicine, Kunming University of Science and Technology, Kunming, 650500, China
| | - Yong-Yan Wang
- Faculty of Medicine, Kunming University of Science and Technology, Kunming, 650500, China
| | - Xiu-Ying He
- Institute of Neurological Disease, Department of Anesthesiology, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China.
| | - Xiao-Ming Zhao
- Faculty of Medicine, Kunming University of Science and Technology, Kunming, 650500, China.
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11
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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] [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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12
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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] [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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13
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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] [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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14
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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: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [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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15
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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: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [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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16
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Chen GL, Li J, Zhang J, Zeng B. To Be or Not to Be an Ion Channel: Cryo-EM Structures Have a Say. Cells 2023; 12:1870. [PMID: 37508534 PMCID: PMC10378246 DOI: 10.3390/cells12141870] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/13/2023] [Accepted: 07/16/2023] [Indexed: 07/30/2023] Open
Abstract
Ion channels are the second largest class of drug targets after G protein-coupled receptors. In addition to well-recognized ones like voltage-gated Na/K/Ca channels in the heart and neurons, novel ion channels are continuously discovered in both excitable and non-excitable cells and demonstrated to play important roles in many physiological processes and diseases such as developmental disorders, neurodegenerative diseases, and cancer. However, in the field of ion channel discovery, there are an unignorable number of published studies that are unsolid and misleading. Despite being the gold standard of a functional assay for ion channels, electrophysiological recordings are often accompanied by electrical noise, leak conductance, and background currents of the membrane system. These unwanted signals, if not treated properly, lead to the mischaracterization of proteins with seemingly unusual ion-conducting properties. In the recent ten years, the technical revolution of cryo-electron microscopy (cryo-EM) has greatly advanced our understanding of the structures and gating mechanisms of various ion channels and also raised concerns about the pore-forming ability of some previously identified channel proteins. In this review, we summarize cryo-EM findings on ion channels with molecular identities recognized or disputed in recent ten years and discuss current knowledge of proposed channel proteins awaiting cryo-EM analyses. We also present a classification of ion channels according to their architectures and evolutionary relationships and discuss the possibility and strategy of identifying more ion channels by analyzing structures of transmembrane proteins of unknown function. We propose that cross-validation by electrophysiological and structural analyses should be essentially required for determining molecular identities of novel ion channels.
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Affiliation(s)
- Gui-Lan Chen
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
| | - Jian Li
- College of Pharmaceutical Sciences, Gannan Medical University, Ganzhou 341000, China
| | - Jin Zhang
- School of Basic Medical Sciences, Nanchang University, Nanchang 330031, China
| | - Bo Zeng
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
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17
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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: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [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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18
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Cai W, Li P, Gu M, Xu H. Lysosomal Ion Channels and Lysosome-Organelle Interactions. Handb Exp Pharmacol 2023; 278:93-108. [PMID: 36882602 DOI: 10.1007/164_2023_640] [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: 03/09/2023]
Abstract
Intracellular organelles exchange their luminal contents with each other via both vesicular and non-vesicular mechanisms. By forming membrane contact sites (MCSs) with ER and mitochondria, lysosomes mediate bidirectional transport of metabolites and ions between lysosomes and organelles that regulate lysosomal physiology, movement, membrane remodeling, and membrane repair. In this chapter, we will first summarize the current knowledge of lysosomal ion channels and then discuss the molecular and physiological mechanisms that regulate lysosome-organelle MCS formation and dynamics. We will also discuss the roles of lysosome-ER and lysosome-mitochondria MCSs in signal transduction, lipid transport, Ca 2+ transfer, membrane trafficking, and membrane repair, as well as their roles in lysosome-related pathologies.
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Affiliation(s)
- Weijie Cai
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
| | - Ping Li
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
| | - Mingxue Gu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dun Neurological Research Institute, Houston, TX, USA
| | - Haoxing Xu
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dun Neurological Research Institute, Houston, TX, USA. .,Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China. .,Department of Cardiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
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19
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Abstract
Parkinson's disease (PD) is clinically, pathologically, and genetically heterogeneous, resisting distillation to a single, cohesive disorder. Instead, each affected individual develops a virtually unique form of Parkinson's syndrome. Clinical manifestations consist of variable motor and nonmotor features, and myriad overlaps are recognized with other neurodegenerative conditions. Although most commonly characterized by alpha-synuclein protein pathology throughout the central and peripheral nervous systems, the distribution varies and other pathologies commonly modify PD or trigger similar manifestations. Nearly all PD is genetically influenced. More than 100 genes or genetic loci have been identified, and most cases likely arise from interactions among many common and rare genetic variants. Despite its complex architecture, insights from experimental genetic dissection coalesce to reveal unifying biological themes, including synaptic, lysosomal, mitochondrial, andimmune-mediated mechanisms of pathogenesis. This emerging understanding of Parkinson's syndrome, coupled with advances in biomarkers and targeted therapies, presages successful precision medicine strategies.
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Affiliation(s)
- Hui Ye
- Department of Neurology, Baylor College of Medicine, Houston, Texas, USA; ,
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas, USA
| | - Laurie A Robak
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA;
| | - Meigen Yu
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA;
| | - Matthew Cykowski
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA;
- Department of Neurology, Houston Methodist Hospital, Houston, Texas, USA
| | - Joshua M Shulman
- Department of Neurology, Baylor College of Medicine, Houston, Texas, USA; ,
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA;
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA;
- Center for Alzheimer's and Neurodegenerative Diseases, Baylor College of Medicine, Houston, Texas, USA
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20
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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: 17] [Impact Index Per Article: 17.0] [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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21
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Hu M, Zhou N, Cai W, Xu H. Lysosomal solute and water transport. J Cell Biol 2022; 221:213536. [PMID: 36219209 PMCID: PMC9559593 DOI: 10.1083/jcb.202109133] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 09/05/2022] [Accepted: 09/22/2022] [Indexed: 11/22/2022] Open
Abstract
Lysosomes mediate hydrolase-catalyzed macromolecule degradation to produce building block catabolites for reuse. Lysosome function requires an osmo-sensing machinery that regulates osmolytes (ions and organic solutes) and water flux. During hypoosmotic stress or when undigested materials accumulate, lysosomes become swollen and hypo-functional. As a membranous organelle filled with cargo macromolecules, catabolites, ions, and hydrolases, the lysosome must have mechanisms that regulate its shape and size while coordinating content exchange. In this review, we discussed the mechanisms that regulate lysosomal fusion and fission as well as swelling and condensation, with a focus on solute and water transport mechanisms across lysosomal membranes. Lysosomal H+, Na+, K+, Ca2+, and Cl- channels and transporters sense trafficking and osmotic cues to regulate both solute flux and membrane trafficking. We also provide perspectives on how lysosomes may adjust the volume of themselves, the cytosol, and the cytoplasm through the control of lysosomal solute and water transport.
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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, Ann Arbor, MI.,Liangzhu Laboratory & Zhejiang University Medical Center, Hangzhou, China
| | - Nan Zhou
- 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, Ann Arbor, MI.,Liangzhu Laboratory & Zhejiang University Medical Center, Hangzhou, China
| | - Weijie Cai
- Liangzhu Laboratory & Zhejiang University Medical Center, Hangzhou, China
| | - Haoxing Xu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI.,Liangzhu Laboratory & Zhejiang University Medical Center, Hangzhou, China.,Department of Neurology, Second Affiliated Hospital of Zhejiang University Medical School, Hangzhou, China
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22
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Mechanism of 4-aminopyridine inhibition of the lysosomal channel TMEM175. Proc Natl Acad Sci U S A 2022; 119:e2208882119. [PMID: 36279431 PMCID: PMC9636928 DOI: 10.1073/pnas.2208882119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transmembrane protein 175 (TMEM175) is an evolutionarily distinct lysosomal cation channel whose mutation is associated with the development of Parkinson’s disease. Here, we present a cryoelectron microscopy structure and molecular simulations of TMEM175 bound to 4-aminopyridine (4-AP), the only known small-molecule inhibitor of TMEM175 and a broad K
+
channel inhibitor, as well as a drug approved by the Food and Drug Administration against multiple sclerosis. The structure shows that 4-AP, whose mode of action had not been previously visualized, binds near the center of the ion conduction pathway, in the open state of the channel. Molecular dynamics simulations reveal that this binding site is near the middle of the transmembrane potential gradient, providing a rationale for the voltage-dependent dissociation of 4-AP from TMEM175. Interestingly, bound 4-AP rapidly switches between three predominant binding poses, stabilized by alternate interaction patterns dictated by the twofold symmetry of the channel. Despite this highly dynamic binding mode, bound 4-AP prevents not only ion permeation but also water flow. Together, these studies provide a framework for the rational design of novel small-molecule inhibitors of TMEM175 that might reveal the role of this channel in human lysosomal physiology both in health and disease.
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23
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Parkinson's disease-risk protein TMEM175 is a proton-activated proton channel in lysosomes. Cell 2022; 185:2292-2308.e20. [PMID: 35750034 DOI: 10.1016/j.cell.2022.05.021] [Citation(s) in RCA: 84] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 11/07/2021] [Accepted: 05/24/2022] [Indexed: 02/06/2023]
Abstract
Lysosomes require an acidic lumen between pH 4.5 and 5.0 for effective digestion of macromolecules. This pH optimum is maintained by proton influx produced by the V-ATPase and efflux through an unidentified "H+ leak" pathway. Here we show that TMEM175, a genetic risk factor for Parkinson's disease (PD), mediates the lysosomal H+ leak by acting as a proton-activated, proton-selective channel on the lysosomal membrane (LyPAP). Acidification beyond the normal range potently activated LyPAP to terminate further acidification of lysosomes. An endogenous polyunsaturated fatty acid and synthetic agonists also activated TMEM175 to trigger lysosomal proton release. TMEM175 deficiency caused lysosomal over-acidification, impaired proteolytic activity, and facilitated α-synuclein aggregation in vivo. Mutational and pH normalization analyses indicated that the channel's H+ conductance is essential for normal lysosome function. Thus, modulation of LyPAP by cellular cues may dynamically tune the pH optima of endosomes and lysosomes to regulate lysosomal degradation and PD pathology.
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Teng B, Kaplan JP, Liang Z, Krieger Z, Tu YH, Burendei B, Ward AB, Liman ER. Structural motifs for subtype-specific pH-sensitive gating of vertebrate otopetrin proton channels. eLife 2022; 11:77946. [PMID: 35920807 PMCID: PMC9348849 DOI: 10.7554/elife.77946] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/19/2022] [Indexed: 01/05/2023] Open
Abstract
Otopetrin (OTOP) channels are proton-selective ion channels conserved among vertebrates and invertebrates, with no structural similarity to other ion channels. There are three vertebrate OTOP channels (OTOP1, OTOP2, and OTOP3), of which one (OTOP1) functions as a sour taste receptor. Whether extracellular protons gate OTOP channels, in addition to permeating them, was not known. Here, we compare the functional properties of the three murine OTOP channels using patch-clamp recording and cytosolic pH microfluorimetry. We find that OTOP1 and OTOP3 are both steeply activated by extracellular protons, with thresholds of pHo <6.0 and 5.5, respectively, and kinetics that are pH-dependent. In contrast, OTOP2 channels are broadly active over a large pH range (pH 5 pH 10) and carry outward currents in response to extracellular alkalinization (>pH 9.0). Strikingly, we could change the pH-sensitive gating of OTOP2 and OTOP3 channels by swapping extracellular linkers that connect transmembrane domains. Swaps of extracellular linkers in the N domain, comprising transmembrane domains 1-6, tended to change the relative conductance at alkaline pH of chimeric channels, while swaps within the C domain, containing transmembrane domains 7-12, tended to change the rates of OTOP3 current activation. We conclude that members of the OTOP channel family are proton-gated (acid-sensitive) proton channels and that the gating apparatus is distributed across multiple extracellular regions within both the N and C domains of the channels. In addition to the taste system, OTOP channels are expressed in the vertebrate vestibular and digestive systems. The distinct gating properties we describe may allow them to subserve varying cell-type specific functions in these and other biological systems.
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Affiliation(s)
- Bochuan Teng
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States,Program in Neuroscience, University of Southern CaliforniaLos AngelesUnited States
| | - Joshua P Kaplan
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States,Program in Neuroscience, University of Southern CaliforniaLos AngelesUnited States
| | - Ziyu Liang
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States,Program in Neuroscience, University of Southern CaliforniaLos AngelesUnited States
| | - Zachary Krieger
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States
| | - Yu-Hsiang Tu
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
| | - Batuujin Burendei
- Department of Integrative Structural and Computational Biology, The Scripps Research InstituteLa JollaUnited States
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research InstituteLa JollaUnited States
| | - Emily R Liman
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States,Program in Neuroscience, University of Southern CaliforniaLos AngelesUnited States
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