1
|
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] [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.
Collapse
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.
| |
Collapse
|
2
|
Hu M, Feng X, Liu Q, Liu S, Huang F, Xu H. The ion channels of endomembranes. Physiol Rev 2024; 104:1335-1385. [PMID: 38451235 DOI: 10.1152/physrev.00025.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 02/20/2024] [Accepted: 02/25/2024] [Indexed: 03/08/2024] Open
Abstract
The endomembrane system consists of organellar membranes in the biosynthetic pathway [endoplasmic reticulum (ER), Golgi apparatus, and secretory vesicles] as well as those in the degradative pathway (early endosomes, macropinosomes, phagosomes, autophagosomes, late endosomes, and lysosomes). These endomembrane organelles/vesicles work together to synthesize, modify, package, transport, and degrade proteins, carbohydrates, and lipids, regulating the balance between cellular anabolism and catabolism. Large ion concentration gradients exist across endomembranes: Ca2+ gradients for most endomembrane organelles and H+ gradients for the acidic compartments. Ion (Na+, K+, H+, Ca2+, and Cl-) channels on the organellar membranes control ion flux in response to cellular cues, allowing rapid informational exchange between the cytosol and organelle lumen. Recent advances in organelle proteomics, organellar electrophysiology, and luminal and juxtaorganellar ion imaging have led to molecular identification and functional characterization of about two dozen endomembrane ion channels. For example, whereas IP3R1-3 channels mediate Ca2+ release from the ER in response to neurotransmitter and hormone stimulation, TRPML1-3 and TMEM175 channels mediate lysosomal Ca2+ and H+ release, respectively, in response to nutritional and trafficking cues. This review aims to summarize the current understanding of these endomembrane channels, with a focus on their subcellular localizations, ion permeation properties, gating mechanisms, cell biological functions, and disease relevance.
Collapse
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
| |
Collapse
|
3
|
Chen S, Wang K, Fan Z, Zhou T, Li R, Zhang B, Chen J, Chi J, Wei K, Liu J, Liu Z, Ma J, Dong N, Liu J. Modulation of anti-cardiac fibrosis immune responses by changing M2 macrophages into M1 macrophages. Mol Med 2024; 30:88. [PMID: 38879491 PMCID: PMC11179216 DOI: 10.1186/s10020-024-00858-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 06/10/2024] [Indexed: 06/19/2024] Open
Abstract
BACKGROUND Macrophages play a crucial role in the development of cardiac fibrosis (CF). Although our previous studies have shown that glycogen metabolism plays an important role in macrophage inflammatory phenotype, the role and mechanism of modifying macrophage phenotype by regulating glycogen metabolism and thereby improving CF have not been reported. METHODS Here, we took glycogen synthetase kinase 3β (GSK3β) as the target and used its inhibitor NaW to enhance macrophage glycogen metabolism, transform M2 phenotype into anti-fibrotic M1 phenotype, inhibit fibroblast activation into myofibroblasts, and ultimately achieve the purpose of CF treatment. RESULTS NaW increases the pH of macrophage lysosome through transmembrane protein 175 (TMEM175) and caused the release of Ca2+ through the lysosomal Ca2+ channel mucolipin-2 (Mcoln2). At the same time, the released Ca2+ activates TFEB, which promotes glucose uptake by M2 and further enhances glycogen metabolism. NaW transforms the M2 phenotype into the anti-fibrotic M1 phenotype, inhibits fibroblasts from activating myofibroblasts, and ultimately achieves the purpose of treating CF. CONCLUSION Our data indicate the possibility of modifying macrophage phenotype by regulating macrophage glycogen metabolism, suggesting a potential macrophage-based immunotherapy against CF.
Collapse
Affiliation(s)
- Shiqi Chen
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Kan Wang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Zhengfeng Fan
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Tingwen Zhou
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Rui Li
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Bingxia Zhang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Jie Chen
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Jiangyang Chi
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Keke Wei
- Department of Immunology, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, 430030, China
| | - Jincheng Liu
- Department of Biochemistry & Molecular Biology, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, 430030, China
| | - Zongtao Liu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Jingwei Ma
- Department of Immunology, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, 430030, China.
| | - Nianguo Dong
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
- Key Laboratory of Organ Transplantation, Ministry of Education, NHC Key Laboratory of Organ Transplantation, Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, China.
| | - Junwei Liu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| |
Collapse
|
4
|
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.
Collapse
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.
| |
Collapse
|
5
|
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.
Collapse
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.
| |
Collapse
|
6
|
DeCoursey TE. Transcendent Aspects of Proton Channels. Annu Rev Physiol 2024; 86:357-377. [PMID: 37931166 PMCID: PMC10938948 DOI: 10.1146/annurev-physiol-042222-023242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
A handful of biological proton-selective ion channels exist. Some open at positive or negative membrane potentials, others open at low or high pH, and some are light activated. This review focuses on common features that result from the unique properties of protons. Proton conduction through water or proteins differs qualitatively from that of all other ions. Extraordinary proton selectivity is needed to ensure that protons permeate and other ions do not. Proton selectivity arises from a proton pathway comprising a hydrogen-bonded chain that typically includes at least one titratable amino acid side chain. The enormously diverse functions of proton channels in disparate regions of the phylogenetic tree can be summarized by considering the chemical and electrical consequences of proton flux across membranes. This review discusses examples of cells in which proton efflux serves to increase pHi, decrease pHo, control the membrane potential, generate action potentials, or compensate transmembrane movement of electrical charge.
Collapse
Affiliation(s)
- Thomas E DeCoursey
- Department of Physiology & Biophysics, Rush University, Chicago, Illinois, USA;
| |
Collapse
|
7
|
Kariev AM, Green ME. Water, Protons, and the Gating of Voltage-Gated Potassium Channels. MEMBRANES 2024; 14:37. [PMID: 38392664 PMCID: PMC10890431 DOI: 10.3390/membranes14020037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/17/2024] [Accepted: 01/23/2024] [Indexed: 02/24/2024]
Abstract
Ion channels are ubiquitous throughout all forms of life. Potassium channels are even found in viruses. Every cell must communicate with its surroundings, so all cells have them, and excitable cells, in particular, especially nerve cells, depend on the behavior of these channels. Every channel must be open at the appropriate time, and only then, so that each channel opens in response to the stimulus that tells that channel to open. One set of channels, including those in nerve cells, responds to voltage. There is a standard model for the gating of these channels that has a section of the protein moving in response to the voltage. However, there is evidence that protons are moving, rather than protein. Water is critical as part of the gating process, although it is hard to see how this works in the standard model. Here, we review the extensive evidence of the importance of the role of water and protons in gating these channels. Our principal example, but by no means the only example, will be the Kv1.2 channel. Evidence comes from the effects of D2O, from mutations in the voltage sensing domain, as well as in the linker between that domain and the gate, and at the gate itself. There is additional evidence from computations, especially quantum calculations. Structural evidence comes from X-ray studies. The hydration of ions is critical in the transfer of ions in constricted spaces, such as the gate region and the pore of a channel; we will see how the structure of the hydrated ion fits with the structure of the channel. In addition, there is macroscopic evidence from osmotic experiments and streaming current measurements. The combined evidence is discussed in the context of a model that emphasizes the role of protons and water in gating these channels.
Collapse
Affiliation(s)
- Alisher M Kariev
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA
| | - Michael E Green
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA
| |
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Tajima S, Kim YS, Fukuda M, Jo Y, Wang PY, Paggi JM, Inoue M, Byrne EFX, Kishi KE, Nakamura S, Ramakrishnan C, Takaramoto S, Nagata T, Konno M, Sugiura M, Katayama K, Matsui TE, Yamashita K, Kim S, Ikeda H, Kim J, Kandori H, Dror RO, Inoue K, Deisseroth K, Kato HE. Structural basis for ion selectivity in potassium-selective channelrhodopsins. Cell 2023; 186:4325-4344.e26. [PMID: 37652010 PMCID: PMC7615185 DOI: 10.1016/j.cell.2023.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 05/11/2023] [Accepted: 08/07/2023] [Indexed: 09/02/2023]
Abstract
KCR channelrhodopsins (K+-selective light-gated ion channels) have received attention as potential inhibitory optogenetic tools but more broadly pose a fundamental mystery regarding how their K+ selectivity is achieved. Here, we present 2.5-2.7 Å cryo-electron microscopy structures of HcKCR1 and HcKCR2 and of a structure-guided mutant with enhanced K+ selectivity. Structural, electrophysiological, computational, spectroscopic, and biochemical analyses reveal a distinctive mechanism for K+ selectivity; rather than forming the symmetrical filter of canonical K+ channels achieving both selectivity and dehydration, instead, three extracellular-vestibule residues within each monomer form a flexible asymmetric selectivity gate, while a distinct dehydration pathway extends intracellularly. Structural comparisons reveal a retinal-binding pocket that induces retinal rotation (accounting for HcKCR1/HcKCR2 spectral differences), and design of corresponding KCR variants with increased K+ selectivity (KALI-1/KALI-2) provides key advantages for optogenetic inhibition in vitro and in vivo. Thus, discovery of a mechanism for ion-channel K+ selectivity also provides a framework for next-generation optogenetics.
Collapse
Affiliation(s)
- Seiya Tajima
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Yoon Seok Kim
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Masahiro Fukuda
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - YoungJu Jo
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Peter Y Wang
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Joseph M Paggi
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Masatoshi Inoue
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Eamon F X Byrne
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Koichiro E Kishi
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Seiwa Nakamura
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | | | - Shunki Takaramoto
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Takashi Nagata
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Masae Konno
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Masahiro Sugiura
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan
| | - Kota Katayama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan
| | - Toshiki E Matsui
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Keitaro Yamashita
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Suhyang Kim
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Hisako Ikeda
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Jaeah Kim
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan; OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Japan
| | - Ron O Dror
- Department of Computer Science, Stanford University, Stanford, CA, USA; Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA, USA; CNC Program, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA; Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA.
| | - Hideaki E Kato
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo, Japan; FOREST, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan.
| |
Collapse
|
10
|
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.
Collapse
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.)
| |
Collapse
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
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: 6] [Impact Index Per Article: 6.0] [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.
Collapse
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
| |
Collapse
|
13
|
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] [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.
Collapse
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.
| |
Collapse
|
14
|
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.
Collapse
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.
| |
Collapse
|
15
|
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.
Collapse
|
16
|
Killer M, Finocchio G, Mertens HDT, Svergun DI, Pardon E, Steyaert J, Löw C. Cryo-EM Structure of an Atypical Proton-Coupled Peptide Transporter: Di- and Tripeptide Permease C. Front Mol Biosci 2022; 9:917725. [PMID: 35898305 PMCID: PMC9309889 DOI: 10.3389/fmolb.2022.917725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 06/16/2022] [Indexed: 11/16/2022] Open
Abstract
Proton-coupled Oligopeptide Transporters (POTs) of the Major Facilitator Superfamily (MFS) mediate the uptake of short di- and tripeptides in all phyla of life. POTs are thought to constitute the most promiscuous class of MFS transporters, with the potential to transport more than 8400 unique substrates. Over the past two decades, transport assays and biophysical studies have shown that various orthologues and paralogues display differences in substrate selectivity. The E. coli genome codes for four different POTs, known as Di- and tripeptide permeases A-D (DtpA-D). DtpC was shown previously to favor positively charged peptides as substrates. In this study, we describe, how we determined the structure of the 53 kDa DtpC by cryogenic electron microscopy (cryo-EM), and provide structural insights into the ligand specificity of this atypical POT. We collected and analyzed data on the transporter fused to split superfolder GFP (split sfGFP), in complex with a 52 kDa Pro-macrobody and with a 13 kDa nanobody. The latter sample was more stable, rigid and a significant fraction dimeric, allowing us to reconstruct a 3D volume of DtpC at a resolution of 2.7 Å. This work provides a molecular explanation for the selectivity of DtpC, and highlights the value of small and rigid fiducial markers such as nanobodies for structure determination of low molecular weight integral membrane proteins lacking soluble domains.
Collapse
Affiliation(s)
- Maxime Killer
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Molecular Biology Laboratory (EMBL), Hamburg Unit C/o Deutsches Elektronen Synchrotron (DESY), Hamburg, Germany
- Collaboration for Joint PhD Degree Between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Giada Finocchio
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Molecular Biology Laboratory (EMBL), Hamburg Unit C/o Deutsches Elektronen Synchrotron (DESY), Hamburg, Germany
| | - Haydyn D. T. Mertens
- Molecular Biology Laboratory (EMBL), Hamburg Unit C/o Deutsches Elektronen Synchrotron (DESY), Hamburg, Germany
| | - Dmitri I. Svergun
- Molecular Biology Laboratory (EMBL), Hamburg Unit C/o Deutsches Elektronen Synchrotron (DESY), Hamburg, Germany
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Christian Löw
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Molecular Biology Laboratory (EMBL), Hamburg Unit C/o Deutsches Elektronen Synchrotron (DESY), Hamburg, Germany
- *Correspondence: Christian Löw,
| |
Collapse
|
17
|
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: 77] [Impact Index Per Article: 38.5] [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.
Collapse
|
18
|
Oh S, Marinelli F, Zhou W, Lee J, Choi HJ, Kim M, Faraldo-Gómez JD, Hite RK. Differential ion dehydration energetics explains selectivity in the non-canonical lysosomal K + channel TMEM175. eLife 2022; 11:75122. [PMID: 35608336 PMCID: PMC9129878 DOI: 10.7554/elife.75122] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 05/01/2022] [Indexed: 12/31/2022] Open
Abstract
Structures of the human lysosomal K+ channel transmembrane protein 175 (TMEM175) in open and closed states revealed a novel architecture lacking the canonical K+ selectivity filter motif present in previously known K+ channel structures. A hydrophobic constriction composed of four isoleucine residues was resolved in the pore and proposed to serve as the gate in the closed state, and to confer ion selectivity in the open state. Here, we achieve higher-resolution structures of the open and closed states and employ molecular dynamics simulations to analyze the conducting properties of the putative open state, demonstrating that it is permeable to K+ and, to a lesser degree, also Na+. Both cations must dehydrate significantly to penetrate the narrow hydrophobic constriction, but ion flow is assisted by a favorable electrostatic field generated by the protein that spans the length of the pore. The balance of these opposing energetic factors explains why permeation is feasible, and why TMEM175 is selective for K+ over Na+, despite the absence of the canonical selectivity filter. Accordingly, mutagenesis experiments reveal an exquisite sensitivity of the channel to perturbations that mitigate the constriction. Together, these data reveal a novel mechanism for selective permeation of ions by TMEM175 that is unlike that of other K+ channels.
Collapse
Affiliation(s)
- SeCheol Oh
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Fabrizio Marinelli
- Theoretical Molecular Biophysics Section, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Wenchang Zhou
- Theoretical Molecular Biophysics Section, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Jooyeon Lee
- Department of Chemistry, Chungbuk National University, Cheongju-si, Republic of Korea
| | - Ho Jeong Choi
- Department of Chemistry, Chungbuk National University, Cheongju-si, Republic of Korea
| | - Min Kim
- Department of Chemistry, Chungbuk National University, Cheongju-si, Republic of Korea
| | - José D Faraldo-Gómez
- Theoretical Molecular Biophysics Section, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Richard K Hite
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| |
Collapse
|
19
|
Cryo-EM structures of a LptDE transporter in complex with Pro-macrobodies offer insight into lipopolysaccharide translocation. Nat Commun 2022; 13:1826. [PMID: 35383177 PMCID: PMC8983717 DOI: 10.1038/s41467-022-29459-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 03/11/2022] [Indexed: 11/13/2022] Open
Abstract
Lipopolysaccharides are major constituents of the extracellular leaflet in the bacterial outer membrane and form an effective physical barrier for environmental threats and for antibiotics in Gram-negative bacteria. The last step of LPS insertion via the Lpt pathway is mediated by the LptD/E protein complex. Detailed insights into the architecture of LptDE transporter complexes have been derived from X-ray crystallography. However, no structure of a laterally open LptD transporter, a transient state that occurs during LPS release, is available to date. Here, we report a cryo-EM structure of a partially opened LptDE transporter in complex with rigid chaperones derived from nanobodies, at 3.4 Å resolution. In addition, a subset of particles allows to model a structure of a laterally fully opened LptDE complex. Our work offers insights into the mechanism of LPS insertion, provides a structural framework for the development of antibiotics targeting LptD and describes a highly rigid chaperone scaffold to enable structural biology of challenging protein targets. Lateral opening of the LptDE transporter in the outer membrane of Gram-negative bacteria is necessary for insertion of lipopolysaccharides. Here, Botte et al. report a cryo-EM structure of a partially opened LptDE transporter, in complex with rigid chaperones derived from nanobodies.
Collapse
|
20
|
Zheng W, Shen C, Wang L, Rawson S, Xie WJ, Nist-Lund C, Wu J, Shen Z, Xia S, Holt JR, Wu H, Fu TM. pH regulates potassium conductance and drives a constitutive proton current in human TMEM175. SCIENCE ADVANCES 2022; 8:eabm1568. [PMID: 35333573 PMCID: PMC8956256 DOI: 10.1126/sciadv.abm1568] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 02/03/2022] [Indexed: 06/01/2023]
Abstract
Human TMEM175, a noncanonical potassium (K+) channel in endolysosomes, contributes to their pH stability and is implicated in the pathogenesis of Parkinson's disease (PD). Structurally, the TMEM175 family exhibits an architecture distinct from canonical potassium channels, as it lacks the typical TVGYG selectivity filter. Here, we show that human TMEM175 not only exhibits pH-dependent structural changes that reduce K+ permeation at acidic pH but also displays proton permeation. TMEM175 constitutively conducts K+ at pH 7.4 but displays reduced K+ permeation at lower pH. In contrast, proton current through TMEM175 increases with decreasing pH because of the increased proton gradient. Molecular dynamics simulation, structure-based mutagenesis, and electrophysiological analysis suggest that K+ ions and protons share the same permeation pathway. The M393T variant of human TMEM175 associated with PD shows reduced function in both K+ and proton permeation. Together, our structural and electrophysiological analysis reveals a mechanism of TMEM175 regulation by pH.
Collapse
Affiliation(s)
- Wang Zheng
- Departments of Otolaryngology and Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Chen Shen
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Longfei Wang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Shaun Rawson
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Wen Jun Xie
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
| | - Carl Nist-Lund
- Departments of Otolaryngology and Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jason Wu
- Departments of Otolaryngology and Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Zhangfei Shen
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Shiyu Xia
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Jeffrey R. Holt
- Departments of Otolaryngology and Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Hao Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Tian-Min Fu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| |
Collapse
|
21
|
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: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [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.
Collapse
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.
| |
Collapse
|
22
|
Lynch CI, Klesse G, Rao S, Tucker SJ, Sansom MSP. Water Nanoconfined in a Hydrophobic Pore: Molecular Dynamics Simulations of Transmembrane Protein 175 and the Influence of Water Models. ACS NANO 2021; 15:19098-19108. [PMID: 34784172 PMCID: PMC7612143 DOI: 10.1021/acsnano.1c06443] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Water molecules within biological ion channels are in a nanoconfined environment and therefore exhibit behaviors which differ from that of bulk water. Here, we investigate the phenomenon of hydrophobic gating, the process by which a nanopore may spontaneously dewet to form a "vapor lock" if the pore is sufficiently hydrophobic and/or narrow. This occurs without steric occlusion of the pore. Using molecular dynamics simulations with both rigid fixed-charge and polarizable (AMOEBA) force fields, we investigate this wetting/dewetting behavior in the transmembrane protein 175 ion channel. We examine how a range of rigid fixed-charge and polarizable water models affect wetting/dewetting in both the wild-type structure and in mutants chosen to cover a range of nanopore radii and pore-lining hydrophobicities. Crucially, we find that the rigid fixed-charge water models lead to similar wetting/dewetting behaviors, but that the polarizable water model resulted in an increased wettability of the hydrophobic gating region of the pore. This has significant implications for molecular simulations of nanoconfined water, as it implies that polarizability may need to be included if we are to gain detailed mechanistic insights into wetting/dewetting processes. These findings are of importance for the design of functionalized biomimetic nanopores (e.g., sensing or desalination) as well as for furthering our understanding of the mechanistic processes underlying biological ion channel function.
Collapse
Affiliation(s)
- Charlotte I. Lynch
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, UK, OX1 3QU
| | - Gianni Klesse
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, UK, OX1 3PU
| | - Shanlin Rao
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, UK, OX1 3QU
| | - Stephen J. Tucker
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, UK, OX1 3PU
| | - Mark S. P. Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, UK, OX1 3QU
| |
Collapse
|
23
|
Translocation of TMEM175 Lysosomal Potassium Channel to the Plasma Membrane by Dynasore Compounds. Int J Mol Sci 2021; 22:ijms221910515. [PMID: 34638858 PMCID: PMC8508992 DOI: 10.3390/ijms221910515] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/21/2021] [Accepted: 09/25/2021] [Indexed: 12/15/2022] Open
Abstract
TMEM175 (transmembrane protein 175) coding sequence variants are associated with increased risk of Parkinson’s disease. TMEM175 is the ubiquitous lysosomal K+ channel regulated by growth factor receptor signaling and direct interaction with protein kinase B (PKB/Akt). In the present study, we show that the expression of mouse TMEM175 results in very small K+ currents through the plasma membrane in Xenopus laevis oocytes, in good accordance with the previously reported intracellular localization of the channel. However, the application of the dynamin inhibitor compounds, dynasore or dyngo-4a, substantially increased TMEM175 currents measured by the two-electrode voltage clamp method. TMEM175 was more permeable to cesium than potassium ions, voltage-dependently blocked by 4-aminopyridine (4-AP), and slightly inhibited by extracellular acidification. Immunocytochemistry experiments indicated that dyngo-4a increased the amount of epitope-tagged TMEM175 channel on the cell surface. The coexpression of dominant-negative dynamin, and the inhibition of clathrin- or caveolin-dependent endocytosis increased TMEM175 current much less than dynasore. Therefore, dynamin-independent pharmacological effects of dynasore may also contribute to the action on the channel. TMEM175 current rapidly decays after the withdrawal of dynasore, raising the possibility that an efficient internalization mechanism removes the channel from the plasma membrane. Dyngo-4a induced about 20-fold larger TMEM175 currents than the PKB activator SC79, or the coexpression of a constitutively active mutant PKB with the channel. In contrast, the allosteric PKB inhibitor MK2206 diminished the TMEM175 current in the presence of dyngo-4a. These data suggest that, in addition to the lysosomes, PKB-dependent regulation also influences TMEM175 current in the plasma membrane.
Collapse
|
24
|
Tyerman SD, McGaughey SA, Qiu J, Yool AJ, Byrt CS. Adaptable and Multifunctional Ion-Conducting Aquaporins. ANNUAL REVIEW OF PLANT BIOLOGY 2021; 72:703-736. [PMID: 33577345 DOI: 10.1146/annurev-arplant-081720-013608] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Aquaporins function as water and neutral solute channels, signaling hubs, disease virulence factors, and metabolon components. We consider plant aquaporins that transport ions compared to some animal counterparts. These are candidates for important, as yet unidentified, cation and anion channels in plasma, tonoplast, and symbiotic membranes. For those individual isoforms that transport ions, water, and gases, the permeability spans 12 orders of magnitude. This requires tight regulation of selectivity via protein interactions and posttranslational modifications. A phosphorylation-dependent switch between ion and water permeation in AtPIP2;1 might be explained by coupling between the gates of the four monomer water channels and the central pore of the tetramer. We consider the potential for coupling between ion and water fluxes that could form the basis of an electroosmotic transducer. A grand challenge in understanding the roles of ion transporting aquaporins is their multifunctional modes that are dependent on location, stress, time, and development.
Collapse
Affiliation(s)
- Stephen D Tyerman
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia; ,
| | - Samantha A McGaughey
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 0200, Australia; ,
| | - Jiaen Qiu
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia; ,
| | - Andrea J Yool
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia 5005, Australia;
| | - Caitlin S Byrt
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 0200, Australia; ,
| |
Collapse
|
25
|
Checchetto V, Leanza L, De Stefani D, Rizzuto R, Gulbins E, Szabo I. Mitochondrial K + channels and their implications for disease mechanisms. Pharmacol Ther 2021; 227:107874. [PMID: 33930454 DOI: 10.1016/j.pharmthera.2021.107874] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 04/12/2021] [Indexed: 02/06/2023]
Abstract
The field of mitochondrial ion channels underwent a rapid development during the last decade, thanks to the molecular identification of some of the nuclear-encoded organelle channels and to advances in strategies allowing specific pharmacological targeting of these proteins. Thereby, genetic tools and specific drugs aided definition of the relevance of several mitochondrial channels both in physiological as well as pathological conditions. Unfortunately, in the case of mitochondrial K+ channels, efforts of genetic manipulation provided only limited results, due to their dual localization to mitochondria and to plasma membrane in most cases. Although the impact of mitochondrial K+ channels on human diseases is still far from being genuinely understood, pre-clinical data strongly argue for their substantial role in the context of several pathologies, including cardiovascular and neurodegenerative diseases as well as cancer. Importantly, these channels are druggable targets, and their in-depth investigation could thus pave the way to the development of innovative small molecules with huge therapeutic potential. In the present review we summarize the available experimental evidence that mechanistically link mitochondrial potassium channels to the above pathologies and underline the possibility of exploiting them for therapy.
Collapse
Affiliation(s)
| | - Luigi Leanza
- Department of Biology, University of Padova, Italy
| | | | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Italy
| | - Erich Gulbins
- Department of Molecular Biology, University of Duisburg-Essen, Germany
| | - Ildiko Szabo
- Department of Biology, University of Padova, Italy; CNR Institute of Neurosciences, Italy.
| |
Collapse
|
26
|
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.
Collapse
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
| |
Collapse
|
27
|
Wie J, Liu Z, Song H, Tropea TF, Yang L, Wang H, Liang Y, Cang C, Aranda K, Lohmann J, Yang J, Lu B, Chen-Plotkin AS, Luk KC, Ren D. A growth-factor-activated lysosomal K + channel regulates Parkinson's pathology. Nature 2021; 591:431-437. [PMID: 33505021 DOI: 10.1038/s41586-021-03185-z] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 12/10/2020] [Indexed: 12/11/2022]
Abstract
Lysosomes have fundamental physiological roles and have previously been implicated in Parkinson's disease1-5. However, how extracellular growth factors communicate with intracellular organelles to control lysosomal function is not well understood. Here we report a lysosomal K+ channel complex that is activated by growth factors and gated by protein kinase B (AKT) that we term lysoKGF. LysoKGF consists of a pore-forming protein TMEM175 and AKT: TMEM175 is opened by conformational changes in, but not the catalytic activity of, AKT. The minor allele at rs34311866, a common variant in TMEM175, is associated with an increased risk of developing Parkinson's disease and reduces channel currents. Reduction in lysoKGF function predisposes neurons to stress-induced damage and accelerates the accumulation of pathological α-synuclein. By contrast, the minor allele at rs3488217-another common variant of TMEM175, which is associated with a decreased risk of developing Parkinson's disease-produces a gain-of-function in lysoKGF during cell starvation, and enables neuronal resistance to damage. Deficiency in TMEM175 leads to a loss of dopaminergic neurons and impairment in motor function in mice, and a TMEM175 loss-of-function variant is nominally associated with accelerated rates of cognitive and motor decline in humans with Parkinson's disease. Together, our studies uncover a pathway by which extracellular growth factors regulate intracellular organelle function, and establish a targetable mechanism by which common variants of TMEM175 confer risk for Parkinson's disease.
Collapse
Affiliation(s)
- Jinhong Wie
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Zhenjiang Liu
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Haikun Song
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Thomas F Tropea
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Lu Yang
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
| | - Huanhuan Wang
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
| | - Yuling Liang
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Chunlei Cang
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Kimberly Aranda
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Joey Lohmann
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Jing Yang
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
| | - Boxun Lu
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Alice S Chen-Plotkin
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Kelvin C Luk
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
| | - Dejian Ren
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
| |
Collapse
|