1
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Holm CM, Topaktas AB, Dannesboe J, Pless SA, Heusser SA. Dynamic conformational changes of acid-sensing ion channels in different desensitizing conditions. Biophys J 2024; 123:2122-2135. [PMID: 38549370 DOI: 10.1016/j.bpj.2024.03.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/21/2024] [Accepted: 03/26/2024] [Indexed: 04/18/2024] Open
Abstract
Acid-sensing ion channels (ASICs) are proton-gated cation channels that contribute to fast synaptic transmission and have roles in fear conditioning and nociception. Apart from activation at low pH, ASIC1a also undergoes several types of desensitization, including acute desensitization, which terminates activation; steady-state desensitization, which occurs at sub-activating proton concentrations and limits subsequent activation; and tachyphylaxis, which results in a progressive decrease in response during a series of activations. Structural insights from a desensitized state of ASIC1 have provided great spatial detail, but dynamic insights into conformational changes in different desensitizing conditions are largely missing. Here, we use electrophysiology and voltage-clamp fluorometry to follow the functional changes of the pore along with conformational changes at several positions in the extracellular and upper transmembrane domain via cysteine-labeled fluorophores. Acute desensitization terminates activation in wild type, but introducing an N414K mutation in the β11-12 linker of mouse ASIC1a interfered with this process. The mutation also affected steady-state desensitization and led to pronounced tachyphylaxis. Although the extracellular domain of this mutant remained sensitive to pH and underwent pH-dependent conformational changes, these conformational changes did not necessarily lead to desensitization. N414K-containing channels also remained sensitive to a known peptide modulator that increases steady-state desensitization, indicating that the mutation only reduced, but not precluded, desensitization. Together, this study contributes to our understanding of the fundamental properties of ASIC1a desensitization, emphasizing the complex interplay between the conformational changes of the extracellular domain and the pore during channel activation and desensitization.
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Affiliation(s)
- Caroline Marcher Holm
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Asli B Topaktas
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Johs Dannesboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stephan A Pless
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Stephanie A Heusser
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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2
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Cristofori-Armstrong B, Budusan E, Smith JJ, Reynaud S, Voll K, Chassagnon IR, Durek T, Rash LD. Revealing molecular determinants governing mambalgin-3 pharmacology at acid-sensing ion channel 1 variants. Cell Mol Life Sci 2024; 81:266. [PMID: 38880807 DOI: 10.1007/s00018-024-05276-2] [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: 01/22/2024] [Revised: 04/19/2024] [Accepted: 05/12/2024] [Indexed: 06/18/2024]
Abstract
Acid-sensing ion channels (ASICs) are trimeric proton-gated cation channels that play a role in neurotransmission and pain sensation. The snake venom-derived peptides, mambalgins, exhibit potent analgesic effects in rodents by inhibiting central ASIC1a and peripheral ASIC1b. Despite their distinct species- and subtype-dependent pharmacology, previous structure-function studies have focussed on the mambalgin interaction with ASIC1a. Currently, the specific channel residues responsible for this pharmacological profile, and the mambalgin pharmacophore at ASIC1b remain unknown. Here we identify non-conserved residues at the ASIC1 subunit interface that drive differences in the mambalgin pharmacology from rat ASIC1a to ASIC1b, some of which likely do not make peptide binding interactions. Additionally, an amino acid variation below the core binding site explains potency differences between rat and human ASIC1. Two regions within the palm domain, which contribute to subtype-dependent effects for mambalgins, play key roles in ASIC gating, consistent with subtype-specific differences in the peptides mechanism. Lastly, there is a shared primary mambalgin pharmacophore for ASIC1a and ASIC1b activity, with certain peripheral peptide residues showing variant-specific significance for potency. Through our broad mutagenesis studies across various species and subtype variants, we gain a more comprehensive understanding of the pharmacophore and the intricate molecular interactions that underlie ligand specificity. These insights pave the way for the development of more potent and targeted peptide analogues required to advance our understating of human ASIC1 function and its role in disease.
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Affiliation(s)
- Ben Cristofori-Armstrong
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Elena Budusan
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Jennifer J Smith
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
- Genentech, 1 DNA Way, South San Francisco, CA, 94080, United States
| | - Steve Reynaud
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
- In Extenso Innovation Growth, Lyon, France
| | - Kerstin Voll
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
- Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Str. 65, 88397, Biberach an der Riß, Germany
| | - Irène R Chassagnon
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
- Servatus Ltd. Coolum Beach, Coolum Beach, QLD, Australia
| | - Thomas Durek
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Lachlan D Rash
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia.
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3
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Purohit R, Couch T, MacLean DM. Proline substitutions in the ASIC1 β11-12 linker slow desensitization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.09.593312. [PMID: 38798386 PMCID: PMC11118455 DOI: 10.1101/2024.05.09.593312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Desensitization is a prominent feature of nearly all ligand gated ion channels. Acid-sensing ion channels (ASIC) undergo desensitization within hundreds of milliseconds to seconds upon continual extracellular acidification. The ASIC mechanism of desensitization is primarily due to the isomerization or "flipping" of a short linker joining the 11th and 12th beta sheets in the extracellular domain. In the resting and active states this β11-12 linker adopts an "upward" conformation while in the desensitized conformation the linker assumes a "downward" state. To accommodate this "downward" state, specific peptide bonds within the linker adopt either trans-like or cis-like conformations. Since proline-containing peptide bonds undergo cis-trans isomerization very slowly, we hypothesized that introducing proline residues in the linker may slow or even abolish ASIC desensitization, potentially providing a valuable research tools. Proline substitutions in the chicken ASIC1 β11-12 linker (L414P and Y416P) slowed desensitization decays approximately 100 to 1000-fold as measured in excised patches. Both L414P and Y416P shifted the steady state desensitization curves to more acidic pHs while activation curves and ion selectivity of these slow-desensitizing currents were largely unaffected. To investigate the functional stoichiometry of desensitization in the trimeric ASIC, we created families of L414P and Y416P concatemers with zero, one, two or three proline substitutions in all possible configurations. Introducing one or two L414P or Y416P mutations only slightly attenuated desensitization, suggesting that conformational changes in the remaining faster wild type subunits were sufficient to desensitize the channel. These data highlight the unusual cis-trans isomerization mechanism of ASIC desensitization and support a model where a single subunit is sufficient to desensitize the entire channel.
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Affiliation(s)
- Rutambhara Purohit
- Department of Pharmacology and Physiology, University of Rochester Medical Center
| | - Tyler Couch
- Department of Pharmacology and Physiology, University of Rochester Medical Center
| | - David M MacLean
- Department of Pharmacology and Physiology, University of Rochester Medical Center
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4
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Cullinan MM, Klipp RC, Camenisch A, Bankston JR. Dynamic landscape of the intracellular termini of acid-sensing ion channel 1a. eLife 2023; 12:RP90755. [PMID: 38054969 PMCID: PMC10699805 DOI: 10.7554/elife.90755] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023] Open
Abstract
Acid-sensing ion channels (ASICs) are trimeric proton-gated sodium channels. Recent work has shown that these channels play a role in necroptosis following prolonged acidic exposure like occurs in stroke. The C-terminus of ASIC1a is thought to mediate necroptotic cell death through interaction with receptor interacting serine threonine kinase 1 (RIPK1). This interaction is hypothesized to be inhibited at rest via an interaction between the C- and N-termini which blocks the RIPK1 binding site. Here, we use two transition metal ion FRET methods to investigate the conformational dynamics of the termini at neutral and acidic pH. We do not find evidence that the termini are close enough to be bound while the channel is at rest and find that the termini may modestly move closer together during acidification. At rest, the N-terminus adopts a conformation parallel to the membrane about 10 Å away. The distal end of the C-terminus may also spend time close to the membrane at rest. After acidification, the proximal portion of the N-terminus moves marginally closer to the membrane whereas the distal portion of the C-terminus swings away from the membrane. Together these data suggest that a new hypothesis for RIPK1 binding during stroke is needed.
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Affiliation(s)
- Megan M Cullinan
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Robert C Klipp
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | | | - John R Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
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5
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Rook ML, McCullock TW, Couch T, Lueck JD, MacLean DM. Photomodulation of the ASIC1a acidic pocket destabilizes the open state. Protein Sci 2023; 32:e4800. [PMID: 37805833 PMCID: PMC10599103 DOI: 10.1002/pro.4800] [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: 10/29/2022] [Revised: 09/25/2023] [Accepted: 10/03/2023] [Indexed: 10/09/2023]
Abstract
Acid-sensing ion channels (ASICs) are important players in detecting extracellular acidification throughout the brain and body. ASICs have large extracellular domains containing two regions replete with acidic residues: the acidic pocket, and the palm domain. In the resting state, the acidic pocket is in an expanded conformation but collapses in low pH conditions as the acidic side chains are neutralized. Thus, extracellular acidification has been hypothesized to collapse the acidic pocket that, in turn, ultimately drives channel activation. However, several observations run counter to this idea. To explore how collapse or mobility of the acidic pocket is linked to channel gating, we employed two distinct tools. First, we incorporated the photocrosslinkable noncanonical amino acids (ncAAs) 4-azido-L-phenylalanine (AzF) or 4-benzoyl-L-phenylalanine (BzF) into several positions in the acidic pocket. At both E315 and Y318, AzF incorporation followed by UV irradiation led to right shifts in pH response curves and accelerations of desensitization and deactivation, consistent with restrictions of acidic pocket mobility destabilizing the open state. Second, we reasoned that because Cl- ions are found in the open and desensitized structures but absent in the resting state structures, Cl- substitution would provide insight into how stability of the pocket is linked to gating. Anion substitution resulted in faster deactivation and desensitization, consistent with the acidic pocket regulating the stability of the open state. Taken together, our data support a model where acidic pocket collapse is not essential for channel activation. Rather, collapse of the acidic pocket influences the stability of the open state of the pore.
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Affiliation(s)
- Matthew L. Rook
- Department of Pharmacology and Physiology, School of Medicine and DentistryUniversity of RochesterRochesterNew YorkUSA
| | - Tyler W. McCullock
- Department of Pharmacology and Physiology, School of Medicine and DentistryUniversity of RochesterRochesterNew YorkUSA
| | - Tyler Couch
- Department of Pharmacology and Physiology, School of Medicine and DentistryUniversity of RochesterRochesterNew YorkUSA
| | - John D. Lueck
- Department of Pharmacology and Physiology, School of Medicine and DentistryUniversity of RochesterRochesterNew YorkUSA
- Deparment of Neurology, School of Medicine and DentistryUniversity of RochesterRochesterNew YorkUSA
- Center for RNA BiologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - David M. MacLean
- Department of Pharmacology and Physiology, School of Medicine and DentistryUniversity of RochesterRochesterNew YorkUSA
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6
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Cullinan MM, Klipp RC, Camenisch A, Bankston JR. Dynamic landscape of the intracellular termini of acid-sensing ion channel 1a. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.05.547693. [PMID: 37461628 PMCID: PMC10350031 DOI: 10.1101/2023.07.05.547693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Acid-sensing ion channels (ASICs) are trimeric proton-gated sodium channels. Recently it has been shown that these channels play a role in necroptosis following prolonged acidic exposure like occurs in stroke. The C-terminus of the channel is thought to mediate necroptotic cell death through interaction with receptor interacting serine threonine kinase 1 (RIPK1). This interaction is hypothesized to be inhibited at rest via an interaction between the C-terminus and the N-terminus which blocks the RIPK1 binding site. Here, we use a combination of two transition metal ion FRET methods to investigate the conformational dynamics of the termini while the channel is closed and desensitized. We do not find evidence that the termini are close enough to be bound while the channel is at rest and find that the termini may modestly move closer together when desensitized. At rest, the N-terminus adopts a conformation parallel to the membrane about 10 Å away. The distal end of the C-terminus may also spend time close to the membrane at rest. After acidification, the proximal portion of the N-terminus moves marginally closer to the membrane whereas the distal portion of the C-terminus swings away from the membrane. Together these data suggest that a new hypothesis for RIPK1 binding during stroke is needed.
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Affiliation(s)
- Megan M Cullinan
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Robert C Klipp
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Abigail Camenisch
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - John R Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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7
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Zhang Z, Chen M, Zhan W, Chen Y, Wang T, Chen Z, Fu Y, Zhao G, Mao D, Ruan J, Yuan FL. Acid-sensing ion channel 1a modulation of apoptosis in acidosis-related diseases: implications for therapeutic intervention. Cell Death Discov 2023; 9:330. [PMID: 37666823 PMCID: PMC10477349 DOI: 10.1038/s41420-023-01624-6] [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: 06/14/2023] [Revised: 07/28/2023] [Accepted: 08/22/2023] [Indexed: 09/06/2023] Open
Abstract
Acid-sensing ion channel 1a (ASIC1a), a prominent member of the acid-sensing ion channel (ASIC) superfamily activated by extracellular protons, is ubiquitously expressed throughout the human body, including the nervous system and peripheral tissues. Excessive accumulation of Ca2+ ions via ASIC1a activation may occur in the acidified microenvironment of blood or local tissues. ASIC1a-mediated Ca2+‑induced apoptosis has been implicated in numerous pathologies, including neurological disorders, cancer, and rheumatoid arthritis. This review summarizes the role of ASIC1a in the modulation of apoptosis via various signaling pathways across different disease states to provide insights for future studies on the underlying mechanisms and development of therapeutic strategies.
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Affiliation(s)
- Zhenyu Zhang
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Minnan Chen
- Nantong First People's Hospital, Nantong, 226001, China
| | - Wenjing Zhan
- The Key Laboratory of Anti-Inflammatory and Immune Medicine, Anhui Medical University, Hefei, 230032, China
| | - Yuechun Chen
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Tongtong Wang
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Zhonghua Chen
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Yifei Fu
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Gang Zhao
- Orthopaedic Institute, Wuxi 9th People's Hospital Affiliated to Soochow University, Wuxi, 214062, China
| | - Dong Mao
- Orthopaedic Institute, Wuxi 9th People's Hospital Affiliated to Soochow University, Wuxi, 214062, China.
| | - Jingjing Ruan
- Nantong First People's Hospital, Nantong, 226001, China.
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, People's Republic of China.
| | - Feng-Lai Yuan
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China.
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8
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Cheng YR, Chi CH, Lee CH, Lin SH, Min MY, Chen CC. Probing the Effect of Acidosis on Tether-Mode Mechanotransduction of Proprioceptors. Int J Mol Sci 2023; 24:12783. [PMID: 37628964 PMCID: PMC10454156 DOI: 10.3390/ijms241612783] [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: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
Proprioceptors are low-threshold mechanoreceptors involved in perceiving body position and strain bearing. However, the physiological response of proprioceptors to fatigue- and muscle-acidosis-related disturbances remains unknown. Here, we employed whole-cell patch-clamp recordings to probe the effect of mild acidosis on the mechanosensitivity of the proprioceptive neurons of dorsal root ganglia (DRG) in mice. We cultured neurite-bearing parvalbumin-positive (Pv+) DRG neurons on a laminin-coated elastic substrate and examined mechanically activated currents induced through substrate deformation-driven neurite stretch (SDNS). The SDNS-induced inward currents (ISDNS) were indentation depth-dependent and significantly inhibited by mild acidification (pH 7.2~6.8). The acid-inhibiting effect occurred in neurons with an ISDNS sensitive to APETx2 (an ASIC3-selective antagonist) inhibition, but not in those with an ISNDS resistant to APETx2. Detailed subgroup analyses revealed ISDNS was expressed in 59% (25/42) of Parvalbumin-positive (Pv+) DRG neurons, 90% of which were inhibited by APETx2. In contrast, an acid (pH 6.8)-induced current (IAcid) was expressed in 76% (32/42) of Pv+ DRG neurons, 59% (21/32) of which were inhibited by APETx2. Together, ASIC3-containing channels are highly heterogenous and differentially contribute to the ISNDS and IAcid among Pv+ proprioceptors. In conclusion, our findings highlight the importance of ASIC3-containing ion channels in the physiological response of proprioceptors to acidic environments.
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Affiliation(s)
- Yuan-Ren Cheng
- Department of Life Science, National Taiwan University, Taipei 10090, Taiwan;
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Chih-Hung Chi
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Cheng-Han Lee
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Shing-Hong Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Ming-Yuan Min
- Department of Life Science, National Taiwan University, Taipei 10090, Taiwan;
| | - Chih-Cheng Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
- Neuroscience Program of Academia Sinica, Academia Sinica, Taipei 11529, Taiwan
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9
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Zhang L, Wang X, Chen J, Sheng S, Kleyman TR. Extracellular intersubunit interactions modulate epithelial Na + channel gating. J Biol Chem 2023; 299:102914. [PMID: 36649907 PMCID: PMC9975279 DOI: 10.1016/j.jbc.2023.102914] [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: 09/07/2022] [Revised: 12/13/2022] [Accepted: 01/12/2023] [Indexed: 01/15/2023] Open
Abstract
Epithelial Na+ channels (ENaCs) and related channels have large extracellular domains where specific factors interact and induce conformational changes, leading to altered channel activity. However, extracellular structural transitions associated with changes in ENaC activity are not well defined. Using crosslinking and two-electrode voltage clamp in Xenopus oocytes, we identified several pairs of functional intersubunit contacts where mouse ENaC activity was modulated by inducing or breaking a disulfide bond between introduced Cys residues. Specifically, crosslinking E499C in the β-subunit palm domain and N510C in the α-subunit palm domain activated ENaC, whereas crosslinking βE499C with αQ441C in the α-subunit thumb domain inhibited ENaC. We determined that bridging βE499C to αN510C or αQ441C altered the Na+ self-inhibition response via distinct mechanisms. Similar to bridging βE499C and αQ441C, we found that crosslinking palm domain αE557C with thumb domain γQ398C strongly inhibited ENaC activity. In conclusion, we propose that certain residues at specific subunit interfaces form microswitches that convey a conformational wave during ENaC gating and its regulation.
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Affiliation(s)
- Lei Zhang
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Nephrology, Hunan Key Laboratory of Kidney Disease and Blood Purification, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Xueqi Wang
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Nephrology, Hunan Key Laboratory of Kidney Disease and Blood Purification, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Jingxin Chen
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Shaohu Sheng
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
| | - Thomas R Kleyman
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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10
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Komarova MS, Bukharev AR, Potapieva NN, Tikhonov DB. Modulation of Slow Desensitization (Tachyphylaxis) of Acid-Sensing Ion Channel (ASIC)1a. Cell Mol Neurobiol 2023; 43:771-783. [PMID: 35201495 DOI: 10.1007/s10571-022-01207-6] [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: 09/30/2021] [Accepted: 02/11/2022] [Indexed: 02/03/2023]
Abstract
Among the proton-activated channels of the ASIC family, ASIC1a exhibits a specific tachyphylaxis phenomenon in the form of a progressive decrease in the response amplitude during a series of activations. This process is well known, but its mechanism is poorly understood. Here, we demonstrated a partial reversibility of this effect using long-term whole-cell recording of CHO cells transfected with rASIC1a cDNA. Thus, tachyphylaxis represents a slow desensitization of ASIC1a. Prolonged acidifications provided the same recovery from slow desensitization as short acidifications of the same frequency. Slow desensitization and steady-state desensitization are independent processes although the latter attenuates the development of the former. We found that drugs which facilitate ASIC1a activation (e.g., amitriptyline) cause an enhancement of slow desensitization, while inhibition of ASIC1a by 9-aminoacridine attenuates this process. Overall, for a broad variety of exposures, including increased calcium concentration, different pH conditions, and modulating drugs, we found a correlation between their effects on ASIC1a response amplitude and the development of slow desensitization. Thus, our results demonstrate that slow desensitization occurs only when ASIC1a is in the open state.
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Affiliation(s)
- Margarita S Komarova
- Laboratory of Biophysics of Synaptic Processes, I.M Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Andrey R Bukharev
- Laboratory of Biophysics of Synaptic Processes, I.M Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Natalia N Potapieva
- Laboratory of Biophysics of Synaptic Processes, I.M Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Denis B Tikhonov
- Laboratory of Biophysics of Synaptic Processes, I.M Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia.
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11
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Osei-Owusu J, Ruan Z, Mihaljević L, Matasic DS, Chen KH, Lü W, Qiu Z. Molecular mechanism underlying desensitization of the proton-activated chloride channel PAC. eLife 2022; 11:e82955. [PMID: 36547405 PMCID: PMC9779784 DOI: 10.7554/elife.82955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022] Open
Abstract
Desensitization is a common property of membrane receptors, including ion channels. The newly identified proton-activated chloride (PAC) channel plays an important role in regulating the pH and size of organelles in the endocytic pathway, and is also involved in acid-induced cell death. However, how the PAC channel desensitizes is largely unknown. Here, we show by patch-clamp electrophysiological studies that PAC (also known as TMEM206/ASOR) undergoes pH-dependent desensitization upon prolonged acid exposure. Through structure-guided and comprehensive mutagenesis, we identified several residues critical for PAC desensitization, including histidine (H) 98, glutamic acid (E) 94, and aspartic acid (D) 91 at the extracellular extension of the transmembrane helix 1 (TM1), as well as E107, D109, and E250 at the extracellular domain (ECD)-transmembrane domain (TMD) interface. Structural analysis and molecular dynamic simulations revealed extensive interactions between residues at the TM1 extension and those at the ECD-TMD interface. These interactions likely facilitate PAC desensitization by stabilizing the desensitized conformation of TM1, which undergoes a characteristic rotational movement from the resting and activated states to the desensitized state. Our studies establish a new paradigm of channel desensitization in this ubiquitously expressed ion channel and pave the way for future investigation of its relevance in cellular physiology and disease.
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Affiliation(s)
- James Osei-Owusu
- Department of Physiology, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Zheng Ruan
- Department of Structural Biology, Van Andel InstituteGrand RapidsUnited States
| | - Ljubica Mihaljević
- Department of Physiology, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Daniel S Matasic
- Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Kevin Hong Chen
- Department of Physiology, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Wei Lü
- Department of Structural Biology, Van Andel InstituteGrand RapidsUnited States
| | - Zhaozhu Qiu
- Department of Physiology, Johns Hopkins University School of MedicineBaltimoreUnited States
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of MedicineBaltimoreUnited States
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12
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Verkest C, Salinas M, Diochot S, Deval E, Lingueglia E, Baron A. Mechanisms of Action of the Peptide Toxins Targeting Human and Rodent Acid-Sensing Ion Channels and Relevance to Their In Vivo Analgesic Effects. Toxins (Basel) 2022; 14:toxins14100709. [PMID: 36287977 PMCID: PMC9612379 DOI: 10.3390/toxins14100709] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 09/30/2022] [Accepted: 10/02/2022] [Indexed: 11/16/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are voltage-independent H+-gated cation channels largely expressed in the nervous system of rodents and humans. At least six isoforms (ASIC1a, 1b, 2a, 2b, 3 and 4) associate into homotrimers or heterotrimers to form functional channels with highly pH-dependent gating properties. This review provides an update on the pharmacological profiles of animal peptide toxins targeting ASICs, including PcTx1 from tarantula and related spider toxins, APETx2 and APETx-like peptides from sea anemone, and mambalgin from snake, as well as the dimeric protein snake toxin MitTx that have all been instrumental to understanding the structure and the pH-dependent gating of rodent and human cloned ASICs and to study the physiological and pathological roles of native ASICs in vitro and in vivo. ASICs are expressed all along the pain pathways and the pharmacological data clearly support a role for these channels in pain. ASIC-targeting peptide toxins interfere with ASIC gating by complex and pH-dependent mechanisms sometimes leading to opposite effects. However, these dual pH-dependent effects of ASIC-inhibiting toxins (PcTx1, mambalgin and APETx2) are fully compatible with, and even support, their analgesic effects in vivo, both in the central and the peripheral nervous system, as well as potential effects in humans.
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Affiliation(s)
- Clément Verkest
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
- Department of Anesthesiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Miguel Salinas
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
| | - Sylvie Diochot
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
| | - Emmanuel Deval
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
| | - Eric Lingueglia
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
| | - Anne Baron
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
- Correspondence:
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13
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MacLean DM, Soto E. Editorial: ASICs: Structure, Function, and Pharmacology. Front Physiol 2022; 13:831830. [PMID: 35173633 PMCID: PMC8841751 DOI: 10.3389/fphys.2022.831830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 01/03/2022] [Indexed: 11/17/2022] Open
Affiliation(s)
- David M. MacLean
- Department of Pharmacology & Physiology, University of Rochester Medical Center, Rochester, NY, United States
| | - Enrique Soto
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
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14
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Rook ML, Ananchenko A, Musgaard M, MacLean DM. Molecular Investigation of Chicken Acid-Sensing Ion Channel 1 β11-12 Linker Isomerization and Channel Kinetics. Front Cell Neurosci 2021; 15:761813. [PMID: 34924957 PMCID: PMC8675884 DOI: 10.3389/fncel.2021.761813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/05/2021] [Indexed: 11/13/2022] Open
Abstract
Structures of the trimeric acid-sensing ion channel have been solved in the resting, toxin-bound open and desensitized states. Within the extracellular domain, there is little difference between the toxin-bound open state and the desensitized state. The main exception is that a loop connecting the 11th and 12th β-strand, just two amino acid residues long, undergoes a significant and functionally critical re-orientation or flipping between the open and desensitized conformations. Here we investigate how specific interactions within the surrounding area influence linker stability in the "flipped" desensitized state using all-atom molecular dynamics simulations. An inherent challenge is bringing the relatively slow channel desensitization and recovery processes (in the milliseconds to seconds) within the time window of all-atom simulations (hundreds of nanoseconds). To accelerate channel behavior, we first identified the channel mutations at either the Leu414 or Asn415 position with the fastest recovery kinetics followed by molecular dynamics simulations of these mutants in a deprotonated state, accelerating recovery. By mutating one residue in the loop and examining the evolution of interactions in the neighbor, we identified a novel electrostatic interaction and validated prior important interactions. Subsequent functional analysis corroborates these findings, shedding light on the molecular factors controlling proton-mediated transitions between functional states of the channel. Together, these data suggest that the flipped loop in the desensitized state is stabilized by interactions from surrounding regions keeping both L414 and N415 in place. Interestingly, very few mutations in the loop allow for equivalent channel kinetics and desensitized state stability. The high degree of sequence conservation in this region therefore indicates that the stability of the ASIC desensitized state is under strong selective pressure and underlines the physiological importance of desensitization.
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Affiliation(s)
- Matthew L. Rook
- Graduate Program in Cellular and Molecular Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, United States
| | - Anna Ananchenko
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Maria Musgaard
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada
| | - David M. MacLean
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, United States
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15
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Alijevic O, Peng Z, Kellenberger S. Changes in H +, K +, and Ca 2+ Concentrations, as Observed in Seizures, Induce Action Potential Signaling in Cortical Neurons by a Mechanism That Depends Partially on Acid-Sensing Ion Channels. Front Cell Neurosci 2021; 15:732869. [PMID: 34720879 PMCID: PMC8553998 DOI: 10.3389/fncel.2021.732869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/27/2021] [Indexed: 11/13/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are activated by extracellular acidification. Because ASIC currents are transient, these channels appear to be ideal sensors for detecting the onset of rapid pH changes. ASICs are involved in neuronal death after ischemic stroke, and in the sensation of inflammatory pain. Ischemia and inflammation are associated with a slowly developing, long-lasting acidification. Recent studies indicate however that ASICs are unable to induce an electrical signaling activity under standard experimental conditions if pH changes are slow. In situations associated with slow and sustained pH drops such as high neuronal signaling activity and ischemia, the extracellular K+ concentration increases, and the Ca2+ concentration decreases. We hypothesized that the concomitant changes in H+, K+, and Ca2+ concentrations may allow a long-lasting ASIC-dependent induction of action potential (AP) signaling. We show that for acidification from pH7.4 to pH7.0 or 6.8 on cultured cortical neurons, the number of action potentials and the firing time increased strongly if the acidification was accompanied by a change to higher K+ and lower Ca2+ concentrations. Under these conditions, APs were also induced in neurons from ASIC1a-/- mice, in which a pH of ≤ 5.0 would be required to activate ASICs, indicating that ASIC activation was not required for the AP induction. Comparison between neurons of different ASIC genotypes indicated that the ASICs modulate the AP induction under such changed ionic conditions. Voltage-clamp measurements of the Na+ and K+ currents in cultured cortical neurons showed that the lowering of the pH inhibited Na+ and K+ currents. In contrast, the lowering of the Ca2+ together with the increase in the K+ concentration led to a hyperpolarizing shift of the activation voltage dependence of voltage-gated Na+ channels. We conclude that the ionic changes observed during high neuronal activity mediate a sustained AP induction caused by the potentiation of Na+ currents, a membrane depolarization due to the changed K+ reversal potential, the activation of ASICs, and possibly effects on other ion channels. Our study describes therefore conditions under which slow pH changes induce neuronal signaling by a mechanism involving ASICs.
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Affiliation(s)
- Omar Alijevic
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Zhong Peng
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Stephan Kellenberger
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
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16
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High-throughput characterization of photocrosslinker-bearing ion channel variants to map residues critical for function and pharmacology. PLoS Biol 2021; 19:e3001321. [PMID: 34491979 PMCID: PMC8448361 DOI: 10.1371/journal.pbio.3001321] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 09/17/2021] [Accepted: 06/10/2021] [Indexed: 12/24/2022] Open
Abstract
Incorporation of noncanonical amino acids (ncAAs) can endow proteins with novel functionalities, such as crosslinking or fluorescence. In ion channels, the function of these variants can be studied with great precision using standard electrophysiology, but this approach is typically labor intensive and low throughput. Here, we establish a high-throughput protocol to conduct functional and pharmacological investigations of ncAA-containing human acid-sensing ion channel 1a (hASIC1a) variants in transiently transfected mammalian cells. We introduce 3 different photocrosslinking ncAAs into 103 positions and assess the function of the resulting 309 variants with automated patch clamp (APC). We demonstrate that the approach is efficient and versatile, as it is amenable to assessing even complex pharmacological modulation by peptides. The data show that the acidic pocket is a major determinant for current decay, and live-cell crosslinking provides insight into the hASIC1a–psalmotoxin 1 (PcTx1) interaction. Further, we provide evidence that the protocol can be applied to other ion channels, such as P2X2 and GluA2 receptors. We therefore anticipate the approach to enable future APC-based studies of ncAA-containing ion channels in mammalian cells. This study describes a method to rapidly screen hundreds of ion channel variants containing non-canonical amino acids. A proof-of-principle introducing photocrosslinking non-canonical amino acids into the human ion channel hASIC1a shows how this approach can provide insights into function and pharmacology.
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17
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Couch T, Berger K, Kneisley DL, McCullock TW, Kammermeier P, Maclean DM. Topography and motion of acid-sensing ion channel intracellular domains. eLife 2021; 10:68955. [PMID: 34292153 PMCID: PMC8341984 DOI: 10.7554/elife.68955] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 07/21/2021] [Indexed: 01/12/2023] Open
Abstract
Acid-sensing ion channels (ASICs) are trimeric cation-selective channels activated by decreases in extracellular pH. The intracellular N and C terminal tails of ASIC1 influence channel gating, trafficking, and signaling in ischemic cell death. Despite several X-ray and cryo-EM structures of the extracellular and transmembrane segments of ASIC1, these important intracellular tails remain unresolved. Here, we describe the coarse topography of the chicken ASIC1 intracellular domains determined by fluorescence resonance energy transfer (FRET), measured using either fluorescent lifetime imaging or patch clamp fluorometry. We find the C terminal tail projects into the cytosol by approximately 35 Å and that the N and C tails from the same subunits are closer than adjacent subunits. Using pH-insensitive fluorescent proteins, we fail to detect any relative movement between the N and C tails upon extracellular acidification but do observe axial motions of the membrane proximal segments toward the plasma membrane. Taken together, our study furnishes a coarse topographic map of the ASIC intracellular domains while providing directionality and context to intracellular conformational changes induced by extracellular acidification.
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Affiliation(s)
- Tyler Couch
- Graduate Program in Cellular and Molecular Pharmacology and Physiology, Reno, United States
| | - Kyle Berger
- Department of Pharmacology and Physiology, University of Rochester Medical Center, New York, United States
| | - Dana L Kneisley
- Department of Pharmacology and Physiology, University of Rochester Medical Center, New York, United States
| | - Tyler W McCullock
- Graduate Program in Cellular and Molecular Pharmacology and Physiology, Reno, United States
| | - Paul Kammermeier
- Department of Pharmacology and Physiology, University of Rochester Medical Center, New York, United States
| | - David M Maclean
- Department of Pharmacology and Physiology, University of Rochester Medical Center, New York, United States
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18
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Rook ML, Miaro M, Couch T, Kneisley DL, Musgaard M, MacLean DM. Mutation of a conserved glutamine residue does not abolish desensitization of acid-sensing ion channel 1. THE JOURNAL OF GENERAL PHYSIOLOGY 2021; 153:212203. [PMID: 34061161 PMCID: PMC8167889 DOI: 10.1085/jgp.202012855] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 05/13/2021] [Indexed: 12/14/2022]
Abstract
Desensitization is a common feature of ligand-gated ion channels, although the molecular cause varies widely between channel types. Mutations that greatly reduce or nearly abolish desensitization have been described for many ligand-gated ion channels, including glutamate, GABA, glycine, and nicotinic receptors, but not for acid-sensing ion channels (ASICs) until recently. Mutating Gln276 to a glycine (Q276G) in human ASIC1a was reported to mostly abolish desensitization at both the macroscopic and the single channel levels, potentially providing a valuable tool for subsequent studies. However, we find that in both human and chicken ASIC1, the effect of Q276G is modest. In chicken ASIC1, the equivalent Q277G slightly reduces desensitization when using pH 6.5 as a stimulus but desensitizes, essentially like wild-type, when using more acidic pH values. In addition, steady-state desensitization is intact, albeit right-shifted, and recovery from desensitization is accelerated. Molecular dynamics simulations indicate that the Gln277 side chain participates in a hydrogen bond network that might stabilize the desensitized conformation. Consistent with this, destabilizing this network with the Q277N or Q277L mutations largely mimics the Q277G phenotype. In human ASIC1a, the Q276G mutation also reduces desensitization, but not to the extent reported previously. Interestingly, the kinetic consequences of Q276G depend on the human variant used. In the common G212 variant, Q276G slows desensitization, while in the rare D212 variant desensitization accelerates. Our data reveal that while the Q/G mutation does not abolish or substantially impair desensitization as previously reported, it does point to unexpected differences between chicken and human ASICs and the need for careful scrutiny before using this mutation in future studies.
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Affiliation(s)
- Matthew L Rook
- Graduate Program in Cellular and Molecular Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY
| | - Megan Miaro
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Tyler Couch
- Graduate Program in Cellular and Molecular Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY
| | - Dana L Kneisley
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY
| | - Maria Musgaard
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - David M MacLean
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY
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19
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Chen Z, Kuenze G, Meiler J, Canessa CM. An arginine residue in the outer segment of hASIC1a TM1 affects both proton affinity and channel desensitization. J Gen Physiol 2021; 153:211986. [PMID: 33851970 PMCID: PMC8050794 DOI: 10.1085/jgp.202012802] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/14/2020] [Accepted: 03/11/2021] [Indexed: 12/25/2022] Open
Abstract
Acid-sensing ion channels (ASICs) respond to changes in pH in the central and peripheral nervous systems and participate in synaptic plasticity and pain perception. Understanding the proton-mediated gating mechanism remains elusive despite the of their structures in various conformational states. We report here that R64, an arginine located in the outer segment of the first transmembrane domain of all three isoforms of mammalian ASICs, markedly impacts the apparent proton affinity of activation and the degree of desensitization from the open and preopen states. Rosetta calculations of free energy changes predict that substitutions of R64 in hASIC1a by aromatic residues destabilize the closed conformation while stabilizing the open conformation. Accordingly, F64 enhances the efficacy of proton-mediated gating of hASIC1a, which increases the apparent pH50 and facilitates channel opening when only one or two subunits are activated. F64 also lengthens the duration of opening events, thus keeping channels open for extended periods of time and diminishing low pH-induced desensitization. Our results indicate that activation of a proton sensor(s) with pH50 equal to or greater than pH 7.2–7.1 opens F64hASIC1a, whereas it induces steady-state desensitization in wildtype channels due to the high energy of activation imposed by R64, which prevents opening of the pore. Together, these findings suggest that activation of a high-affinity proton-sensor(s) and a common gating mechanism may mediate the processes of activation and steady-state desensitization of hASIC1a.
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Affiliation(s)
- Zhuyuan Chen
- Department of Basic Sciences, Tsinghua University School of Medicine, Beijing, China
| | - Georg Kuenze
- Department of Chemistry, Vanderbilt University, Nashville, TN.,Center for Structural Biology, Vanderbilt University, Nashville, TN.,Institute for Drug Discovery, Leipzig University, Leipzig, Germany
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN.,Center for Structural Biology, Vanderbilt University, Nashville, TN.,Department of Pharmacology, Vanderbilt University, Nashville, TN.,Institute for Drug Discovery, Leipzig University, Leipzig, Germany
| | - Cecilia M Canessa
- Department of Basic Sciences, Tsinghua University School of Medicine, Beijing, China.,Cellular and Molecular Physiology, Yale University, New Haven, CT
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20
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Bowie D. Neurotransmitter-gated ion channels, still front and centre stage. J Physiol 2021; 599:389-395. [PMID: 33448020 DOI: 10.1113/jp280800] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Derek Bowie
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, H3G 1Y6, Canada
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21
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Abstract
Combining crosslinking strategies with electrophysiology, biochemistry, and structural in silico analysis is a powerful tool to study transient movements of ion channels during gating. This chapter describes crosslinking in living cells using cysteine and photoactive unnatural amino acids (UAAs) that we have used on glutamate receptor ion channels. Here, we share the protocol for building a perfusion tool to enable rapid chemical modification of glutamate-gated AMPA receptors, optimized for their fast activation. This system can be used to perform state-dependent crosslinking in receptors modified by cysteines or UAA incorporation on the millisecond timescale. Introducing UAAs results in receptors with lower expression levels relative to the introduction of cysteine residues. Reduced expression is principally a challenge for biochemical studies, and we share here our approach to capture the light driven oligomerization of AMPA receptors containing UAA crosslinkers. Finally, we describe strategies for computational analysis to make sense of the crosslinking results in terms of structure and function.
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Affiliation(s)
- Andrew J R Plested
- Institute of Biology, Cellular Biophysics, Humboldt Universität zu Berlin, Berlin, Germany; Leibniz Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
| | - Mette H Poulsen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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22
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Vullo S, Ambrosio N, Kucera JP, Bignucolo O, Kellenberger S. Kinetic analysis of ASIC1a delineates conformational signaling from proton-sensing domains to the channel gate. eLife 2021; 10:66488. [PMID: 33729158 PMCID: PMC8009679 DOI: 10.7554/elife.66488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 03/16/2021] [Indexed: 11/13/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are neuronal Na+ channels that are activated by a drop in pH. Their established physiological and pathological roles, involving fear behaviors, learning, pain sensation, and neurodegeneration after stroke, make them promising targets for future drugs. Currently, the ASIC activation mechanism is not understood. Here, we used voltage-clamp fluorometry (VCF) combined with fluorophore-quencher pairing to determine the kinetics and direction of movements. We show that conformational changes with the speed of channel activation occur close to the gate and in more distant extracellular sites, where they may be driven by local protonation events. Further, we provide evidence for fast conformational changes in a pathway linking protonation sites to the channel pore, in which an extracellular interdomain loop interacts via aromatic residue interactions with the upper end of a transmembrane helix and would thereby open the gate.
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Affiliation(s)
- Sabrina Vullo
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Ambrosio
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Jan P Kucera
- Department of Physiology, University of Bern, Bern, Switzerland
| | - Olivier Bignucolo
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.,SIB, Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Stephan Kellenberger
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
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23
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Molecular mechanism and structural basis of small-molecule modulation of the gating of acid-sensing ion channel 1. Commun Biol 2021; 4:174. [PMID: 33564124 PMCID: PMC7873226 DOI: 10.1038/s42003-021-01678-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 01/07/2021] [Indexed: 01/07/2023] Open
Abstract
Acid-sensing ion channels (ASICs) are proton-gated cation channels critical for neuronal functions. Studies of ASIC1, a major ASIC isoform and proton sensor, have identified acidic pocket, an extracellular region enriched in acidic residues, as a key participant in channel gating. While binding to this region by the venom peptide psalmotoxin modulates channel gating, molecular and structural mechanisms of ASIC gating modulation by small molecules are poorly understood. Here, combining functional, crystallographic, computational and mutational approaches, we show that two structurally distinct small molecules potently and allosterically inhibit channel activation and desensitization by binding at the acidic pocket and stabilizing the closed state of rat/chicken ASIC1. Our work identifies a previously unidentified binding site, elucidates a molecular mechanism of small molecule modulation of ASIC gating, and demonstrates directly the structural basis of such modulation, providing mechanistic and structural insight into ASIC gating, modulation and therapeutic targeting.
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24
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Salinas M, Kessler P, Douguet D, Sarraf D, Tonali N, Thai R, Servent D, Lingueglia E. Mambalgin-1 pain-relieving peptide locks the hinge between α4 and α5 helices to inhibit rat acid-sensing ion channel 1a. Neuropharmacology 2021; 185:108453. [PMID: 33450275 DOI: 10.1016/j.neuropharm.2021.108453] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/04/2020] [Accepted: 01/05/2021] [Indexed: 10/22/2022]
Abstract
Acid-sensing ion channels (ASICs) are proton-gated cationic channels involved in pain and other processes, underscoring the potential therapeutic value of specific inhibitors such as the three-finger toxin mambalgin-1 (Mamb-1) from snake venom. A low-resolution structure of the human-ASIC1a/Mamb-1 complex obtained by cryo-electron microscopy has been recently reported, implementing the structure of the chicken-ASIC1/Mamb-1 complex previously published. Here we combine structure-activity relationship of both the rat ASIC1a channel and the Mamb-1 toxin with a molecular dynamics simulation to obtain a detailed picture at the level of side-chain interactions of the binding of Mamb-1 on rat ASIC1a channels and of its inhibition mechanism. Fingers I and II of Mamb-1 but not the core of the toxin are required for interaction with the thumb domain of ASIC1a, and Lys-8 of finger I potentially interacts with Tyr-358 in the thumb domain. Mamb-1 does not interfere directly with the pH sensor as previously suggested, but locks by several contacts a key hinge between α4 and α5 helices in the thumb domain of ASIC1a to prevent channel opening. Our results provide an improved model of inhibition of mammalian ASIC1a channels by Mamb-1 and clues for further development of optimized ASIC blockers.
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Affiliation(s)
- Miguel Salinas
- Université Côte d'Azur, CNRS, IPMC, LabEx ICST, FHU InovPain, France.
| | - Pascal Kessler
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France
| | - Dominique Douguet
- Université Côte d'Azur, CNRS, IPMC, LabEx ICST, FHU InovPain, France
| | - Daad Sarraf
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France
| | - Nicolo Tonali
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France; CNRS, BioCIS, Université Paris-Saclay, 92290, Châtenay-Malabry, France
| | - Robert Thai
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France
| | - Denis Servent
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France.
| | - Eric Lingueglia
- Université Côte d'Azur, CNRS, IPMC, LabEx ICST, FHU InovPain, France.
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Pan X, Zhu Y, Wu X, Liu L, Ying R, Wang L, Du N, Zhang J, Jin J, Meng X, Dai F, Huang Y. The interaction of ASIC1a and ERS mediates nerve cell apoptosis induced by insulin deficiency. Eur J Pharmacol 2020; 893:173816. [PMID: 33345857 DOI: 10.1016/j.ejphar.2020.173816] [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: 08/30/2020] [Revised: 12/07/2020] [Accepted: 12/11/2020] [Indexed: 10/22/2022]
Abstract
Diabetes-related brain complications are the most serious complications of terminal diabetes. The increasing evidence have showed that the predisposing factor is not only hyperglycemia, but also insulin deficiency. In this study, we demonstrated that insulin deficiency was involved in the apoptosis of nerve cells, and it was related to the interaction between acid-sensitive ion channel 1a (ASIC1a) and endoplasmic reticulum stress (ERS). By silencing C/EBP homologous protein (CHOP) and ASIC1a, the pro-apoptotic effect of insulin deficiency on NS20y cells was relieved. Further research found that the binding of CHOP and C/EBPα was increased in the nucleus of cells cultured without insulin, and C/EBPα was competitively inhibited as a negative regulator of ASIC1a, which further increased the ERS and lead to neuronal apoptosis. In summary, ERS and ASIC1a play an important role in neurological damage caused by insulin deficiency. Our finding may lead to new ideas and treatment of diabetes-related brain complications.
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Affiliation(s)
- Xuesheng Pan
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Hefei, 230032, China
| | - Yueqin Zhu
- Department of Pharmacy, West Branch of the First Affiliated Hospital of University of Science and Technology of China (Anhui Provincial Cancer Hospital), Hefei, 230031, China
| | - Xian Wu
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Hefei, 230032, China
| | - Lan Liu
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Hefei, 230032, China; Department of Pharmacy, Fuyang Hospital of Anhui Medical University, Fuyang, 236000, China
| | - Ruixue Ying
- Department of Endocrinology, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, China
| | - Lili Wang
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Hefei, 230032, China
| | - Na Du
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Hefei, 230032, China
| | - Jin Zhang
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Hefei, 230032, China
| | - Juan Jin
- Department of Pharmacology, School of Basic Medicine, Anhui Medical University. Hefei, 230032, China
| | - Xiaoming Meng
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Hefei, 230032, China
| | - Fang Dai
- Department of Endocrinology, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, China.
| | - Yan Huang
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Hefei, 230032, China.
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Braun N, Sheikh ZP, Pless SA. The current chemical biology tool box for studying ion channels. J Physiol 2020; 598:4455-4471. [DOI: 10.1113/jp276695] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 07/06/2020] [Indexed: 12/13/2022] Open
Affiliation(s)
- N. Braun
- Department of Drug Design and Pharmacology University of Copenhagen Jagtvej 160 Copenhagen 2100 Denmark
| | - Z. P. Sheikh
- Department of Drug Design and Pharmacology University of Copenhagen Jagtvej 160 Copenhagen 2100 Denmark
| | - S. A. Pless
- Department of Drug Design and Pharmacology University of Copenhagen Jagtvej 160 Copenhagen 2100 Denmark
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Rook ML, Musgaard M, MacLean DM. Coupling structure with function in acid-sensing ion channels: challenges in pursuit of proton sensors. J Physiol 2020; 599:417-430. [PMID: 32306405 DOI: 10.1113/jp278707] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/27/2020] [Indexed: 12/25/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are a class of trimeric cation-selective ion channels activated by changes in pH within the physiological range. They are widely expressed in the central and peripheral nervous systems where they participate in a range of physiological and pathophysiological situations such as learning and memory, pain sensation, fear and anxiety, substance abuse and cell death. ASICs are localized to cell bodies and dendrites, including the postsynaptic density, and within the last 5 years several examples of proton-evoked ASIC excitatory postsynaptic currents have emerged. Thus, ASICs have become bona fide neurotransmitter-gated ion channels, activated by the smallest neurotransmitter possible: protons. Here we review how protons are thought to drive the conformational changes associated with ASIC activation and desensitization. In particular, we weigh the evidence for and against the so-called 'acidic pocket' being a vital proton sensor and discuss the emerging role of the β11-12 linker as a desensitization switch or 'molecular clutch'. We also examine how proton-induced conformational changes pose unique challenges to classical molecular dynamics simulations, as well as some possible solutions. Given the emergence of new methodologies and structures, the coming years will probably see many advances in the study of acid-sensing ion channels.
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Affiliation(s)
- Matthew L Rook
- Graduate Program in Cellular and Molecular Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY, 14642, USA
| | - Maria Musgaard
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 75 Laurier Ave E, Ottawa, ON, K1N 6N5, Canada
| | - David M MacLean
- Department of Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY, 14642, USA
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