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Sheng D, Yue CX, Jin F, Wang Y, Ichikawa M, Yu Y, Guo CR, Hattori M. Structural insights into the orthosteric inhibition of P2X receptors by non-ATP analog antagonists. eLife 2024; 12:RP92829. [PMID: 38578670 PMCID: PMC10997329 DOI: 10.7554/elife.92829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024] Open
Abstract
P2X receptors are extracellular ATP-gated ion channels that form homo- or heterotrimers and consist of seven subtypes. They are expressed in various tissues, including neuronal and nonneuronal cells, and play critical roles in physiological processes such as neurotransmission, inflammation, pain, and cancer. As a result, P2X receptors have attracted considerable interest as drug targets, and various competitive inhibitors have been developed. However, although several P2X receptor structures from different subtypes have been reported, the limited structural information of P2X receptors in complex with competitive antagonists hampers the understanding of orthosteric inhibition, hindering the further design and optimization of those antagonists for drug discovery. We determined the cryogenic electron microscopy (cryo-EM) structures of the mammalian P2X7 receptor in complex with two classical competitive antagonists of pyridoxal-5'-phosphate derivatives, pyridoxal-5'-phosphate-6-(2'-naphthylazo-6'-nitro-4',8'-disulfonate) (PPNDS) and pyridoxal phosphate-6-azophenyl-2',5'-disulfonic acid (PPADS), and performed structure-based mutational analysis by patch-clamp recording as well as molecular dynamics (MD) simulations. Our structures revealed the orthosteric site for PPADS/PPNDS, and structural comparison with the previously reported apo- and ATP-bound structures showed how PPADS/PPNDS binding inhibits the conformational changes associated with channel activation. In addition, structure-based mutational analysis identified key residues involved in the PPNDS sensitivity of P2X1 and P2X3, which are known to have higher affinity for PPADS/PPNDS than other P2X subtypes.
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Affiliation(s)
- Danqi Sheng
- State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Bioactive Small Molecules, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Neurobiology, School of Life Sciences, Fudan UniversityShanghaiChina
| | - Chen-Xi Yue
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical UniversityNanjingChina
| | - Fei Jin
- State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Bioactive Small Molecules, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Neurobiology, School of Life Sciences, Fudan UniversityShanghaiChina
| | - Yao Wang
- State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Bioactive Small Molecules, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Neurobiology, School of Life Sciences, Fudan UniversityShanghaiChina
| | - Muneyoshi Ichikawa
- State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan UniversityShanghaiChina
| | - Ye Yu
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical UniversityNanjingChina
| | - Chang-Run Guo
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical UniversityNanjingChina
| | - Motoyuki Hattori
- State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Bioactive Small Molecules, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Neurobiology, School of Life Sciences, Fudan UniversityShanghaiChina
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Shen C, Zhang Y, Cui W, Zhao Y, Sheng D, Teng X, Shao M, Ichikawa M, Wang J, Hattori M. Structural insights into the allosteric inhibition of P2X4 receptors. Nat Commun 2023; 14:6437. [PMID: 37833294 PMCID: PMC10575874 DOI: 10.1038/s41467-023-42164-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 10/01/2023] [Indexed: 10/15/2023] Open
Abstract
P2X receptors are ATP-activated cation channels, and the P2X4 subtype plays important roles in the immune system and the central nervous system, particularly in neuropathic pain. Therefore, P2X4 receptors are of increasing interest as potential drug targets. Here, we report the cryo-EM structures of the zebrafish P2X4 receptor in complex with two P2X4 subtype-specific antagonists, BX430 and BAY-1797. Both antagonists bind to the same allosteric site located at the subunit interface at the top of the extracellular domain. Structure-based mutational analysis by electrophysiology identified the important residues for the allosteric inhibition of both zebrafish and human P2X4 receptors. Structural comparison revealed the ligand-dependent structural rearrangement of the binding pocket to stabilize the binding of allosteric modulators, which in turn would prevent the structural changes of the extracellular domain associated with channel activation. Furthermore, comparison with the previously reported P2X structures of other subtypes provided mechanistic insights into subtype-specific allosteric inhibition.
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Affiliation(s)
- Cheng Shen
- State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Bioactive Small Molecules, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Yuqing Zhang
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Wenwen Cui
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Yimeng Zhao
- State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Bioactive Small Molecules, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China
- Human Phenome Institute, Fudan University, Shanghai, 201203, China
| | - Danqi Sheng
- State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Bioactive Small Molecules, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Xinyu Teng
- State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Bioactive Small Molecules, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Miaoqing Shao
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Muneyoshi Ichikawa
- State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Jin Wang
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China.
| | - Motoyuki Hattori
- State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Bioactive Small Molecules, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China.
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3
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Guo CR, Zhang ZZ, Zhou X, Sun MY, Li TT, Lei YT, Gao YH, Li QQ, Yue CX, Gao Y, Lin YY, Hao CY, Li CZ, Cao P, Zhu MX, Rong MQ, Wang WH, Yu Y. Chronic cough relief by allosteric modulation of P2X3 without taste disturbance. Nat Commun 2023; 14:5844. [PMID: 37730705 PMCID: PMC10511716 DOI: 10.1038/s41467-023-41495-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 09/06/2023] [Indexed: 09/22/2023] Open
Abstract
P2X receptors are cation channels that sense extracellular ATP. Many therapeutic candidates targeting P2X receptors have begun clinical trials or acquired approval for the treatment of refractory chronic cough (RCC) and other disorders. However, the present negative allosteric modulation of P2X receptors is primarily limited to the central pocket or the site below the left flipper domain. Here, we uncover a mechanism of allosteric regulation of P2X3 in the inner pocket of the head domain (IP-HD), and show that the antitussive effects of quercetin and PSFL2915 (our nM-affinity P2X3 inhibitor optimized based on quercetin) on male mice and guinea pigs were achieved by preventing allosteric changes of IP-HD in P2X3. While being therapeutically comparable to the newly licensed P2X3 RCC drug gefapixant, quercetin and PSFL2915 do not have an adverse effect on taste as gefapixant does. Thus, allosteric modulation of P2X3 via IP-HD may be a druggable strategy to alleviate RCC.
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Affiliation(s)
- Chang-Run Guo
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 211198, China
| | - Zhong-Zhe Zhang
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Xing Zhou
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Meng-Yang Sun
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Tian-Tian Li
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Yun-Tao Lei
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Yu-Hao Gao
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Qing-Quan Li
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Chen-Xi Yue
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Yu Gao
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Yi-Yu Lin
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Cui-Yun Hao
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Chang-Zhu Li
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, Hunan, 410004, China
| | - Peng Cao
- Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA
| | - Ming-Qiang Rong
- The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
| | - Wen-Hui Wang
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China.
| | - Ye Yu
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China.
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 211198, China.
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Weinhausen S, Nagel J, Namasivayam V, Spanier C, Abdelrahman A, Hanck T, Hausmann R, Müller CE. Extracellular binding sites of positive and negative allosteric P2X4 receptor modulators. Life Sci 2022; 311:121143. [DOI: 10.1016/j.lfs.2022.121143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/13/2022] [Accepted: 10/27/2022] [Indexed: 11/18/2022]
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Zhang X, Sun MY, Zhang X, Guo CR, Lei YT, Wang WH, Fan YZ, Cao P, Li CZ, Wang R, Li XH, Yu Y, Yang XN. Dynamic recognition of naloxone, morphine and endomorphin1 in the same pocket of µ-opioid receptors. Front Mol Biosci 2022; 9:925404. [PMID: 36052166 PMCID: PMC9424762 DOI: 10.3389/fmolb.2022.925404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 07/04/2022] [Indexed: 11/13/2022] Open
Abstract
Morphine, the most widely used analgesic, relieves severe pain by activating the μ-opioid receptor (MOR), whereas naloxone, with only slight structural changes compared to morphine, exhibits inhibitory effect, and is used to treat opioid abuse. The mechanism by which the MOR distinguishes between the two is unclear. Molecular dynamics (MD) simulations on a 1-μs time scale and metadynamics-enhanced conformational sampling are used here to determine the different interactions of these two ligands with MOR: morphine adjusted its pose by continuously flipping deeper into the pocket, whereas naloxone failed to penetrate deeper because its allyl group conflicts with several residues of MOR. The endogenous peptide ligand endomorphin-1 (EM-1) underwent almost no significant conformational changes during the MD simulations. To validate these processes, we employed GIRK4S143T, a MOR-activated Gβγ-protein effector, in combination with mutagenesis and electrophysiological recordings. We verified the role of some key residues in the dynamic recognition of naloxone and morphine and identified the key residue I322, which leads to differential recognition of morphine and naloxone while assisting EM-1 in activating MOR. Reducing the side chain size of I322 (MORI322A) transformed naloxone from an inhibitor directly into an agonist of MOR, and I322A also significantly attenuated the potency of MOR on EM-1, confirming that binding deep in the pocket is critical for the agonistic effect of MOR. This finding reveals a dynamic mechanism for the response of MOR to different ligands and provides a basis for the discovery of new ligands for MOR at the atomic level.
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Affiliation(s)
- Xin Zhang
- Department of Basic Medicine and Clinical Pharmacy and State Key laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Meng-Yang Sun
- Department of Basic Medicine and Clinical Pharmacy and State Key laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Xue Zhang
- Department of Basic Medicine and Clinical Pharmacy and State Key laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Chang-Run Guo
- Department of Basic Medicine and Clinical Pharmacy and State Key laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Yun-Tao Lei
- Department of Basic Medicine and Clinical Pharmacy and State Key laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Wen-Hui Wang
- Department of Basic Medicine and Clinical Pharmacy and State Key laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Ying-Zhe Fan
- Putuo Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai, China
| | - Peng Cao
- Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Chang-Zhu Li
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, China
| | - Rui Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China
| | - Xing-Hua Li
- Department of Basic Medicine and Clinical Pharmacy and State Key laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
- *Correspondence: Xing-Hua Li, ; Ye Yu, ; Xiao-Na Yang,
| | - Ye Yu
- Department of Basic Medicine and Clinical Pharmacy and State Key laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, Shanghai, China
- *Correspondence: Xing-Hua Li, ; Ye Yu, ; Xiao-Na Yang,
| | - Xiao-Na Yang
- Department of Basic Medicine and Clinical Pharmacy and State Key laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, Shanghai, China
- *Correspondence: Xing-Hua Li, ; Ye Yu, ; Xiao-Na Yang,
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6
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Oken AC, Krishnamurthy I, Savage JC, Lisi NE, Godsey MH, Mansoor SE. Molecular Pharmacology of P2X Receptors: Exploring Druggable Domains Revealed by Structural Biology. Front Pharmacol 2022; 13:925880. [PMID: 35784697 PMCID: PMC9248971 DOI: 10.3389/fphar.2022.925880] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 05/10/2022] [Indexed: 11/18/2022] Open
Abstract
Extracellular ATP is a critical signaling molecule that is found in a wide range of concentrations across cellular environments. The family of nonselective cation channels that sense extracellular ATP, termed P2X receptors (P2XRs), is composed of seven subtypes (P2X1-P2X7) that assemble as functional homotrimeric and heterotrimeric ion channels. Each P2XR is activated by a distinct concentration of extracellular ATP, spanning from high nanomolar to low millimolar. P2XRs are implicated in a variety of physiological and pathophysiological processes in the cardiovascular, immune, and central nervous systems, corresponding to the spatiotemporal expression, regulation, and activation of each subtype. The therapeutic potential of P2XRs is an emerging area of research in which structural biology has seemingly exceeded medicinal chemistry, as there are several published P2XR structures but currently no FDA-approved drugs targeting these ion channels. Cryogenic electron microscopy is ideally suited to facilitate structure-based drug design for P2XRs by revealing and characterizing novel ligand-binding sites. This review covers structural elements in P2XRs including the extracellular orthosteric ATP-binding site, extracellular allosteric modulator sites, channel pore, and cytoplasmic substructures, with an emphasis on potential therapeutic ligand development.
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Affiliation(s)
- Adam C. Oken
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, United States
| | - Ipsita Krishnamurthy
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, United States
| | - Jonathan C. Savage
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, United States
| | - Nicolas E. Lisi
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, United States
| | - Michael H. Godsey
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, United States
| | - Steven E. Mansoor
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, United States
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, United States
- *Correspondence: Steven E. Mansoor,
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7
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Sun MY, Zhang X, Yu PC, Liu D, Yang Y, Cui WW, Yang XN, Lei YT, Li XH, Wang WH, Cao P, Wang HS, Zhu MX, Li CZ, Wang R, Fan YZ, Yu Y. Vanilloid agonist-mediated activation of TRPV1 channels requires coordinated movement of the S1-S4 bundle rather than a quiescent state. Sci Bull (Beijing) 2022; 67:1062-1076. [PMID: 36546250 DOI: 10.1016/j.scib.2022.02.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 01/12/2022] [Accepted: 02/16/2022] [Indexed: 01/07/2023]
Abstract
Transient receptor potential vanilloid1 (TRPV1) channel plays an important role in a wide range of physiological and pathological processes, and a comprehensive understanding of TRPV1 gating will create opportunities for therapeutic intervention. Recent incredible advances in cryo-electron microscopy (cryo-EM) have yielded high-resolution structures of all TRPV subtypes (TRPV1-6) and all of them share highly conserved six transmembrane (TM) domains (S1-S6). As revealed by the open structures of TRPV1 in the presence of a bound vanilloid agonist (capsaicin or resiniferatoxin), TM helicesS1 to S4 form a bundle that remains quiescent during channel activation, highlighting differences in the gating mechanism of TRPV1 and voltage-gated ion channels. Here, however, we argue that the structural dynamics rather than quiescence of S1-S4 domains is necessary for capsaicin-mediated activation of TRPV1. Using fluorescent unnatural amino acid (flUAA) incorporation and voltage-clamp fluorometry (VCF) analysis, we directly observed allostery of the S1-S4 bundle upon capsaicin binding. Covalent occupation of VCF-identified sites, single-channel recording, cell apoptosis analysis, and exploration of the role of PSFL828, a novel non-vanilloid agonist we identified, have collectively confirmed the essential role of this coordinated S1-S4 motility in capsaicin-mediated activation of TRPV1. This study concludes that, in contrast to cryo-EM structural studies, vanilloid agonists are also required for S1-S4 movement during TRPV1 activation. Redefining the gating process of vanilloid agonists and the discovery of new non-vanilloid agonists will allow the evaluation of new strategies aimed at the development of TRPV1 modulators.
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Affiliation(s)
- Meng-Yang Sun
- School of Life Sciences and Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China; Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Xue Zhang
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Peng-Cheng Yu
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Di Liu
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Yang Yang
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Wen-Wen Cui
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiao-Na Yang
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China; College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
| | - Yun-Tao Lei
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Xing-Hua Li
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Wen-Hui Wang
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Peng Cao
- Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Heng-Shan Wang
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Collaborative Innovation Center for Guangxi Ethnic Medicine, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, China
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Chang-Zhu Li
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha 410004, China
| | - Rui Wang
- School of Life Sciences and Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China.
| | - Ying-Zhe Fan
- Putuo Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai 200062, China.
| | - Ye Yu
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China.
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Ma XF, Wang TT, Wang WH, Guan L, Guo CR, Li XH, Lei YT, Fan YZ, Yang XN, Hattori M, Nureki O, Zhu MX, Yu Y, Tian Y, Wang J. The long β2,3-sheets encoded by redundant sequences play an integral role in the channel function of P2X7 receptors. J Biol Chem 2022; 298:102002. [PMID: 35504351 PMCID: PMC9163701 DOI: 10.1016/j.jbc.2022.102002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 04/23/2022] [Accepted: 04/27/2022] [Indexed: 11/26/2022] Open
Abstract
P2X receptors are a class of nonselective cation channels widely distributed in the immune and nervous systems, and their dysfunction is a significant cause of tumors, inflammation, leukemia, and immune diseases. P2X7 is a unique member of the P2X receptor family with many properties that differ from other subtypes in terms of primary sequence, the architecture of N- and C-terminals, and channel function. Here, we suggest that the observed lengthened β2- and β3-sheets and their linker (loop β2,3), encoded by redundant sequences, play an indispensable role in the activation of the P2X7 receptor. We show that deletion of this longer structural element leads to the loss of P2X7 function. Furthermore, by combining mutagenesis, chimera construction, surface expression, and protein stability analysis, we found that the deletion of the longer β2,3-loop affects P2X7 surface expression but, more importantly, that this loop affects channel gating of P2X7. We propose that the longer β2,3-sheets may have a negative regulatory effect on a loop on the head domain and on the structural element formed by E171 and its surrounding regions. Understanding the role of the unique structure of the P2X7 receptor in the gating process will aid in the development of selective drugs targeting this subtype.
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Affiliation(s)
- Xue-Fei Ma
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China; School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Ting-Ting Wang
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Wen-Hui Wang
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Li Guan
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Chang-Run Guo
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Xing-Hua Li
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Yun-Tao Lei
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Ying-Zhe Fan
- Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China
| | - Xiao-Na Yang
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Motoyuki Hattori
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Shanghai Key Laboratory of Bioactive Small Molecules, Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Ye Yu
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China.
| | - Yun Tian
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China.
| | - Jin Wang
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China.
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9
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Immadisetty K, Alenciks J, Kekenes-Huskey PM. Modulation of P2X4 pore closure by magnesium, potassium, and ATP. Biophys J 2022; 121:1134-1142. [PMID: 35248546 PMCID: PMC9034312 DOI: 10.1016/j.bpj.2022.02.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/12/2021] [Accepted: 02/22/2022] [Indexed: 11/30/2022] Open
Abstract
The P2X4 receptor plays a prominent role in cellular responses to extracellular ATP. Through classical all-atom molecular dynamics (MD) simulations totaling 24 μs we have investigated how metal-complexed ATP stabilizes the channel's open state and prevents its closing. We have identified two metal-binding sites, Mg2+ and potassium K+, one at the intersection of the three subunits in the ectodomain (MBS1) and the second one near the ATP-binding site (MBS2), similar to those characterized in Gulf Coast P2X. Our data indicate that when Mg2+ and K+ ions are complexed with ATP, the channel is locked into an open state. Interestingly, irrespective of the number of bound ATP molecules, Mg2+ ions bound to the MBS2 impeded the collapse of the open-state protein to a closed state by stabilizing the ATP-protein interactions. However, when Mg2+ in the MBS2 was replaced with K+ ions, as might be expected when in equilibrium with an extracellular solution, the interactions between the subunits were weakened and the pore collapsed. This collapse was apparent when fewer than two ATPs were bound to MBS2 in the presence of K+. Therefore, the different capacities of common cations to stabilize the channel may underlie a mechanism governing P2X4 channel gating in physiological systems. This study therefore provides structural insights into the differential modulation of ATP activation of P2X4 by Mg2+ and K+.
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10
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Gasparri F, Sarkar D, Bielickaite S, Poulsen MH, Hauser AS, Pless SA. P2X2 receptor subunit interfaces are missense variant hotspots where mutations tend to increase apparent ATP affinity. Br J Pharmacol 2022; 179:3859-3874. [PMID: 35285517 PMCID: PMC9314836 DOI: 10.1111/bph.15830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 01/31/2022] [Accepted: 02/09/2022] [Indexed: 11/30/2022] Open
Abstract
Background and Purpose P2X receptors are trimeric ligand‐gated ion channels that open a cation‐selective pore in response to ATP binding to their large extracellular domain. The seven known P2X subtypes can assemble as homotrimeric or heterotrimeric complexes and contribute to numerous physiological functions, including nociception, inflammation and hearing. The overall structure of P2X receptors is well established, but little is known about the range and prevalence of human genetic variations and the functional implications of specific domains. Experimental Approach Here, we examine the impact of P2X2 receptor inter‐subunit interface missense variants identified in the human population or by structural predictions. We test both single and double mutants through electrophysiological and biochemical approaches. Key Results We demonstrate that predicted extracellular domain inter‐subunit interfaces display a higher‐than‐expected density of missense variations and that the majority of mutations that disrupt putative inter‐subunit interactions result in channels with higher apparent ATP affinity. Lastly, we show that double mutants at the subunit interface show significant energetic coupling, especially if located in close proximity. Conclusion and Implications We provide the first structural mapping of the mutational distribution across the human population in a ligand‐gated ion channel and show that the density of missense mutations is constrained between protein domains, indicating evolutionary selection at the domain level. Our data may indicate that, unlike other ligand‐gated ion channels, P2X2 receptors have evolved an intrinsically high threshold for activation, possibly to allow for additional modulation or as a cellular protection mechanism against overstimulation.
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Affiliation(s)
- Federica Gasparri
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Debayan Sarkar
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Sarune Bielickaite
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Mette Homann Poulsen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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11
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Cui WW, Wang SY, Zhang YQ, Wang Y, Fan YZ, Guo CR, Li XH, Lei YT, Wang WH, Yang XN, Hattori M, Li CZ, Wang J, Yu Y. P2X3-selective mechanism of Gefapixant, a drug candidate for the treatment of refractory chronic cough. Comput Struct Biotechnol J 2022; 20:1642-1653. [PMID: 35465163 PMCID: PMC9014320 DOI: 10.1016/j.csbj.2022.03.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 03/16/2022] [Accepted: 03/27/2022] [Indexed: 11/25/2022] Open
Abstract
The mechanism by which Gefapixant/AF-219 selectively acts on the P2X3 receptor is unclear. The negative allosteric site of AF-219 at P2X3 is also a potent allosteric site for other P2X subtypes. The selectivity of AF-219 for P2X3 is determined by the accessibility of binding site and the internal shape of this pocket. The finding will provide new perspectives for drug design against P2X3-mediated diseases such as RCC.
Gefapixant/AF-219, a selective inhibitor of the P2X3 receptor, is the first new drug other than dextromethorphan to be approved for the treatment of refractory chronic cough (RCC) in nearly 60 years. To date, seven P2X subtypes (P2X1-7) activated by extracellular ATP have been cloned, and subtype selectivity of P2X inhibitors is a prerequisite for reducing side effects. We previously identified the site and mechanism of action of Gefapixant/AF-219 on the P2X3 receptor, which occupies a pocket consisting of the left flipper (LF) and lower body (LB) domains. However, the mechanism by which AF-219 selectively acts on the P2X3 receptor is unknown. Here, we combined mutagenesis, chimera construction, molecular simulations, covalent occupation and chemical synthesis, and find that the negative allosteric site of AF-219 at P2X3 is also present in other P2X subtypes, at least for P2X1, P2X2 and P2X4. By constructing each chimera of AF-219 sensitive P2X3 and insensitive P2X2 subtypes, the insensitive P2X2 subtype was made to acquire the inhibitory properties of AF-219 and AF-353, an analog of AF-219 with higher affinity. Our results suggest that the selectivity of AF-219/AF-353 for P2X3 over the other P2X subtypes is determined by a combination of the accessibility of P2X3 binding site and the internal shape of this pocket, a finding that could provide new perspectives for drug design against P2X3-mediated diseases such as RCC, idiopathic pulmonary fibrosis, hypertension and overactive bladder disorder.
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12
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Sheng D, Hattori M. Recent progress in the structural biology of P2X receptors. Proteins 2022; 90:1779-1785. [PMID: 35023590 DOI: 10.1002/prot.26302] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 01/04/2022] [Accepted: 01/11/2022] [Indexed: 12/27/2022]
Abstract
P2X receptors are ATP-gated trimeric nonselective cation channels that are important for various physiological and pathological processes, including synaptic transmission, pain perception, immune regulation, and apoptosis. Accordingly, they attract a wide range of interest as drug targets, such as those for chronic cough, neuropathic pain, and depression. After the zebrafish P2X4 receptor structure was reported in 2009, various other P2X receptor structures have been reported, extending our understanding of the molecular mechanisms of P2X receptors. This review article describes the recent progress on understanding the structures and mechanisms of P2X receptors, especially of the mechanisms underlying ATP binding and conformational changes during the gating cycle. In addition, since several antagonists for different P2X subtypes have entered into clinical trials, this review also summarizes the binding sites and regulatory mechanisms of these antagonists, which may contribute to new strategies of targeting P2X receptors for drug discovery.
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Affiliation(s)
- Danqi Sheng
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Shanghai Key Laboratory of Bioactive Small Molecules, Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, China
| | - Motoyuki Hattori
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Shanghai Key Laboratory of Bioactive Small Molecules, Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, China
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13
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Yang PL, Li XH, Wang J, Ma XF, Zhou BY, Jiao YF, Wang WH, Cao P, Zhu MX, Li PW, Xiao ZH, Li CZ, Guo CR, Lei YT, Yu Y. GSK1702934A and M085 directly activate TRPC6 via a mechanism of stimulating the extracellular cavity formed by the pore helix and transmembrane helix S6. J Biol Chem 2021; 297:101125. [PMID: 34461094 PMCID: PMC8458982 DOI: 10.1016/j.jbc.2021.101125] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/22/2021] [Accepted: 08/26/2021] [Indexed: 01/20/2023] Open
Abstract
Transient receptor potential canonical (TRPC) channels, as important membrane proteins regulating intracellular calcium (Ca2+i) signaling, are involved in a variety of physiological and pathological processes. Activation and regulation of TRPC are more dependent on membrane or intracellular signals. However, how extracellular signals regulate TRPC6 function remains to be further investigated. Here, we suggest that two distinct small molecules, M085 and GSK1702934A, directly activate TRPC6, both through a mechanism of stimulation of extracellular sites formed by the pore helix (PH) and transmembrane (TM) helix S6. In silico docking scanning of TRPC6 identified three extracellular sites that can bind small molecules, of which only mutations on residues of PH and S6 helix significantly reduced the apparent affinity of M085 and GSK1702934A and attenuated the maximal response of TRPC6 to these two chemicals by altering channel gating of TRPC6. Combing metadynamics, molecular dynamics simulations, and mutagenesis, we revealed that W679, E671, E672, and K675 in the PH and N701 and Y704 in the S6 helix constitute an orthosteric site for the recognition of these two agonists. The importance of this site was further confirmed by covalent modification of amino acid residing at the interface of the PH and S6 helix. Given that three structurally distinct agonists M085, GSK1702934A, and AM-0883, act at this site, as well as the occupancy of lipid molecules at this position found in other TRP subfamilies, it is suggested that the cavity formed by the PH and S6 has an important role in the regulation of TRP channel function by extracellular signals.
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Affiliation(s)
- Pei-Lin Yang
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Xing-Hua Li
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Jin Wang
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Xue-Fei Ma
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
| | - Bo-Ying Zhou
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Yuan-Feng Jiao
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Wen-Hui Wang
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Peng Cao
- Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Michael Xi Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Pei-Wang Li
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, China
| | - Zhi-Hong Xiao
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, China
| | - Chang-Zhu Li
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, China
| | - Chang-Run Guo
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, China.
| | - Yun-Tao Lei
- School of Science, China Pharmaceutical University, Nanjing, China.
| | - Ye Yu
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China.
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14
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Chen PF, Ma XF, Sun LF, Tian Y, Fan YZ, Li P, Xiao Z, Zhu MX, Guo CR, Li C, Yu Y, Wang J. A conserved residue in the P2X4 receptor has a nonconserved function in ATP recognition. J Biol Chem 2021; 296:100655. [PMID: 33901491 PMCID: PMC8166750 DOI: 10.1016/j.jbc.2021.100655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 04/05/2021] [Accepted: 04/08/2021] [Indexed: 12/11/2022] Open
Abstract
Highly conserved amino acids are generally anticipated to have similar functions across a protein superfamily, including that of the P2X ion channels, which are gated by extracellular ATP. However, whether and how these functions are conserved becomes less clear when neighboring amino acids are not conserved. Here, we investigate one such case, focused on the highly conserved residue from P2X4, E118 (rat P2X4 numbering, rP2X4), a P2X subtype associated with human neuropathic pain. When we compared the crystal structures of P2X4 with those of other P2X subtypes, including P2X3, P2X7, and AmP2X, we observed a slightly altered side-chain orientation of E118. We used protein chimeras, double-mutant cycle analysis, and molecular modeling to reveal that E118 forms specific contacts with amino acids in the "beak" region, which facilitates ATP binding to rP2X4. These contacts are not present in other subtypes because of sequence variance in the beak region, resulting in decoupling of this conserved residue from ATP recognition and/or channel gating of P2X receptors. Our study provides an example of a conserved residue with a specific role in functional proteins enabled by adjacent nonconserved residues. The unique role established by the E118-beak region contact provides a blueprint for the development of subtype-specific inhibitors of P2X4.
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Affiliation(s)
- Ping-Fang Chen
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xue-Fei Ma
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China; College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
| | - Liang-Fei Sun
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yun Tian
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
| | - Ying-Zhe Fan
- Putuo Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai, China
| | - Peiwang Li
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, China
| | - Zhihong Xiao
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, China
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Chang-Run Guo
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Changzhu Li
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, China.
| | - Ye Yu
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China; School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China; State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Collaborative Innovation Center for Guangxi Ethnic Medicine, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin, China.
| | - Jin Wang
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China.
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15
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Alberto AVP, da Silva Ferreira NC, Soares RF, Alves LA. Molecular Modeling Applied to the Discovery of New Lead Compounds for P2 Receptors Based on Natural Sources. Front Pharmacol 2020; 11:01221. [PMID: 33117147 PMCID: PMC7553047 DOI: 10.3389/fphar.2020.01221] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/27/2020] [Indexed: 12/24/2022] Open
Abstract
P2 receptors are a family of transmembrane receptors activated by nucleotides and nucleosides. Two classes have been described in mammals, P2X and P2Y, which are implicated in various diseases. Currently, only P2Y12 has medicines approved for clinical use as antiplatelet agents and natural products have emerged as a source of new drugs with action on P2 receptors due to the diversity of chemical structures. In drug discovery, in silico virtual screening (VS) techniques have become popular because they have numerous advantages, which include the evaluation of thousands of molecules against a target, usually proteins, faster and cheaper than classical high throughput screening (HTS). The number of studies using VS techniques has been growing in recent years and has led to the discovery of new molecules of natural origin with action on different P2X and P2Y receptors. Using different algorithms it is possible to obtain information on absorption, distribution, metabolism, toxicity, as well as predictions on biological activity and the lead-likeness of the selected hits. Selected biomolecules may then be tested by molecular dynamics and, if necessary, rationally designed or modified to improve their interaction for the target. The algorithms of these in silico tools are being improved to permit the precision development of new drugs and, in the future, this process will take the front of drug development against some central nervous system (CNS) disorders. Therefore, this review discusses the methodologies of in silico tools concerning P2 receptors, as well as future perspectives and discoveries, such as the employment of artificial intelligence in drug discovery.
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Affiliation(s)
- Anael Viana Pinto Alberto
- Laboratory of Cellular Communication, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | | | - Rafael Ferreira Soares
- Laboratory of Functional Genomics and Bioinformatics, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Luiz Anastacio Alves
- Laboratory of Cellular Communication, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
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16
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Abstract
P2X receptors (P2XRs) are ligand-gated ion channels gated by extracellular adenosine 5'-triphosphate (ATP) and play a critical role in mediating ATP-induced purinergic signaling in physiological and pathological processes. Heterologous expression of P2XR in human embryonic kidney 293 (HEK293) cells and measurement of P2XR-mediated currents using patch-clamp recording technique have been widely used to study the biophysical and pharmacological properties of these receptors. Combination of electrophysiology with site-directed mutagenesis and structural information has shed light on the molecular basis for receptor activation and mechanisms of actions by receptor antagonists and modulators. It is anticipated that such methodologies will continue helping us to provide more mechanistic understanding of P2XRs and to test novel receptor antagonists and allosteric modulators for therapeutical purposes. In this chapter, we describe protocols of transiently or stably expressing the P2XR in HEK293 cells and measuring P2XR-mediated currents by using whole-cell recording.
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17
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Racigh V, Ormazábal A, Palma J, Pierdominici-Sottile G. Positively Charged Residues in the Head Domain of P2X4 Receptors Assist the Binding of ATP. J Chem Inf Model 2020; 60:923-932. [PMID: 31747275 DOI: 10.1021/acs.jcim.9b00856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
P2X receptors are a family of trimeric cationic channels located in the membrane of mammalian cells. They open in response to the binding of ATP. The differences between the closed and open structures have been described in detail for some members of the family. However, the order in which the conformational changes take place as ATP enters the binding cleft, and the residues involved in the intermediate stages, are still unknown. Here, we present the results of umbrella sampling simulations aimed to elucidate the sequence of conformational changes that occur during the reversible binding of ATP to the P2X4 receptor. The simulations also provided information about the interactions that develop in the course of the process. In particular, they revealed the existence of a metastable state which assists the binding. This state is stabilized by positively charged residues located in the head domain of the receptor. Based on these findings, we propose a novel mechanism for the capture of ATP by P2X4 receptors.
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Affiliation(s)
- Vanesa Racigh
- Departamento de Ciencia y Tecnología , Universidad Nacional de Quilmes , Sáenz Peña 352 , B1876BXD Bernal, Buenos Aires , Argentina.,Consejo Nacional de Investigaciones Cientficas y Técnicas , CONICET , B1876BXD Bernal, Buenos Aires , Argentina
| | - Agustín Ormazábal
- Departamento de Ciencia y Tecnología , Universidad Nacional de Quilmes , Sáenz Peña 352 , B1876BXD Bernal, Buenos Aires , Argentina.,Consejo Nacional de Investigaciones Cientficas y Técnicas , CONICET , B1876BXD Bernal, Buenos Aires , Argentina
| | - Juliana Palma
- Departamento de Ciencia y Tecnología , Universidad Nacional de Quilmes , Sáenz Peña 352 , B1876BXD Bernal, Buenos Aires , Argentina.,Consejo Nacional de Investigaciones Cientficas y Técnicas , CONICET , B1876BXD Bernal, Buenos Aires , Argentina
| | - Gustavo Pierdominici-Sottile
- Departamento de Ciencia y Tecnología , Universidad Nacional de Quilmes , Sáenz Peña 352 , B1876BXD Bernal, Buenos Aires , Argentina.,Consejo Nacional de Investigaciones Cientficas y Técnicas , CONICET , B1876BXD Bernal, Buenos Aires , Argentina
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18
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Sun LF, Liu Y, Wang J, Huang LD, Yang Y, Cheng XY, Fan YZ, Zhu MX, Liang H, Tian Y, Wang HS, Guo CR, Yu Y. Altered allostery of the left flipper domain underlies the weak ATP response of rat P2X5 receptors. J Biol Chem 2019; 294:19589-19603. [PMID: 31727741 PMCID: PMC6926468 DOI: 10.1074/jbc.ra119.009959] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/12/2019] [Indexed: 12/31/2022] Open
Abstract
Although the extracellular ATP-gated cation channel purinergic receptor P2X5 is widely expressed in heart, skeletal muscle, and immune and nervous systems in mammals, little is known about its functions and channel-gating activities. This lack of knowledge is due to P2X5's weak ATP responses in several mammalian species, such as humans, rats, and mice. WT human P2X5 (hP2X5Δ328-349) does not respond to ATP, whereas a full-length variant, hP2X5 (hP2X5-FL), containing exon 10 encoding the second hP2X5 transmembrane domain (TM2), does. However, although rat P2X5 (rP2X5) has a full-length TM2, ATP induces only weak currents in rP2X5, which prompted us to investigate the mechanism underlying this small ATP response. Here, we show that single replacements of specific rP2X5 residues with the corresponding residues in hP2X5 (S191F or F195H) significantly enhance the current amplitude of rP2X5. Using a combination of engineered disulfide cross-linking, single-channel recording, and molecular modeling, we interrogated the effects of S191F and F195H substitutions on the allostery of the left flipper (LF) domain. On the basis of our findings, we propose that the bound ATP-induced distinct allostery of the LF domain with that of other functional subtypes has caused the weak ATP response of rP2X5 receptors. The findings of our study provide the prerequisite for future transgenic studies on the physiological and pathological functions of P2X5 receptors.
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Affiliation(s)
- Liang-Fei Sun
- Institute of Medical Sciences and Department of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yan Liu
- Institute of Medical Sciences and Department of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jin Wang
- Institute of Medical Sciences and Department of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Li-Dong Huang
- Institute of Medical Sciences and Department of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yang Yang
- Institute of Medical Sciences and Department of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiao-Yang Cheng
- Institute of Medical Sciences and Department of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ying-Zhe Fan
- Putuo District Center Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai 200026, China
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030
| | - Hong Liang
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China
| | - Yun Tian
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
| | - Heng-Shan Wang
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China
| | - Chang-Run Guo
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Ye Yu
- Institute of Medical Sciences and Department of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
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19
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Li B, Wang J, Cheng X, Liu Y, Yang Y, Yang X, Guo C, Niu Y, Cao P, Lu X, Zhu MX, Tian Y, Yu Y. Molecular mechanism underlying the subtype-selectivity of competitive inhibitor NF110 and its distinct potencies in human and rat P2X3 receptors. Sci Bull (Beijing) 2018; 63:1616-1625. [PMID: 36658853 DOI: 10.1016/j.scib.2018.11.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/08/2018] [Accepted: 11/14/2018] [Indexed: 01/21/2023]
Abstract
P2X receptors are a family of extracellular ATP-gated trimeric cation channels that is widely distributed in human tissues. Quite some drug candidates targeting P2X receptors have entered into preclinical or main phases of clinical trials, but many of them failed due to low subtype-selectivity or species differences in pharmacological activities between human and experimental animals. Here, we identified the distinct inhibitory efficacies of NF110, a competitive inhibitor, between the rat (rP2X3) and human (hP2X3) P2X3 receptors. We demonstrated that this difference is determined by two amino acids located in the dorsal fin (DF) domain of P2X3 receptors. As revealed by mutagenesis, metadynamics, and covalent modification, NF110-mediated rP2X3 inhibition may be through a filling in the cavity formed by the DF, left flipper (LF) and lower body (LB) to partially, rather than fully, occupy the ATP-binding pocket. Moreover, substitution of residues located in the DF and/or LF domains of the rP2X2 receptor, a NF110-insensitive subtype, with the equivalent amino acids of rP2X3, bestowed the sensitivity of rP2X2 to NF110. The critical roles of the DF and LF domains in channel gating of P2X and low conservativity in residue sequences of those two domains raise the possibility that small molecules differentially interacting with the residues of the DF and LF domains of different P2X receptors may modulate channel's activity in a subtype-selective manner. However, the possible species-specificity of P2X inhibitors/modulators makes it more complex when interpreting the preclinical data into clinical researches. Nevertheless, our data provide new insights into the subtype-selectivity of competitive inhibitors and their distinct potencies in the human and experimental animals, both of which are extremely important in the drug discovery of P2X receptors.
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Affiliation(s)
- Bin Li
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China; Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jin Wang
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiaoyang Cheng
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yan Liu
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yang Yang
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiaona Yang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China; School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Changrun Guo
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Youya Niu
- Department of Cell Biology and Genetics, Hunan University of Medicine, Huaihua 418000, China
| | - Peng Cao
- Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Xiangyang Lu
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
| | - Michael X Zhu
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China; State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Science, Guangxi Normal University, Guilin 541004, China
| | - Yun Tian
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China.
| | - Ye Yu
- Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China.
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Abstract
Extracellular ATP-gated P2X receptors are trimeric non-selective cation channels important for many physiological events including immune response and neural transmission. These receptors belong to a unique class of ligand-gated ion channels composed of only six transmembrane helices and a relatively small extracellular domain that harbors three ATP-binding pockets. The crystal structures of P2X receptors, including the recent P2X3 structures representing three different stages of the gating cycle, have provided a compelling structural foundation for understanding how this class of ligand-gated ion channels function. These structures, in combination with numerous functional studies ranging from classic mutagenesis and electrophysiology to modern optogenetic pharmacology, have uncovered unique molecular mechanisms of P2X receptor function. This review article summarizes the current knowledge in P2X receptor activation, especially focusing on the mechanisms underlying ATP-binding, conformational changes in the extracellular domain, and channel gating and desensitization.
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21
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Wang J, Wang Y, Cui WW, Huang Y, Yang Y, Liu Y, Zhao WS, Cheng XY, Sun WS, Cao P, Zhu MX, Wang R, Hattori M, Yu Y. Druggable negative allosteric site of P2X3 receptors. Proc Natl Acad Sci U S A 2018; 115:4939-44. [PMID: 29674445 DOI: 10.1073/pnas.1800907115] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Allosteric modulation provides exciting opportunities for drug discovery of enzymes, ion channels, and G protein-coupled receptors. As cation channels gated by extracellular ATP, P2X receptors have attracted wide attention as new drug targets. Although small molecules targeting P2X receptors have entered into clinical trials for rheumatoid arthritis, cough, and pain, negative allosteric modulation of these receptors remains largely unexplored. Here, combining X-ray crystallography, computational modeling, and functional studies of channel mutants, we identified a negative allosteric site on P2X3 receptors, fostered by the left flipper (LF), lower body (LB), and dorsal fin (DF) domains. Using two structurally analogous subtype-specific allosteric inhibitors of P2X3, AF-353 and AF-219, the latter being a drug candidate under phase II clinical trials for refractory chronic cough and idiopathic pulmonary fibrosis, we defined the molecular interactions between the drugs and receptors and the mechanism by which allosteric changes in the LF, DF, and LB domains modulate ATP activation of P2X3. Our detailed characterization of this druggable allosteric site should inspire new strategies to develop P2X3-specific allosteric modulators for clinical use.
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22
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Allsopp RC, Dayl S, Bin Dayel A, Schmid R, Evans RJ. Mapping the Allosteric Action of Antagonists A740003 and A438079 Reveals a Role for the Left Flipper in Ligand Sensitivity at P2X7 Receptors. Mol Pharmacol 2018. [PMID: 29535152 PMCID: PMC5896373 DOI: 10.1124/mol.117.111021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
P2X7 receptor (P2X7R) activation requires ∼100-fold higher concentrations of ATP than other P2X receptor (P2XR) subtypes. Such high levels are found during cellular stress, and P2X7Rs consequently contribute to a range of pathophysiological conditions. We have used chimeric and mutant P2X7Rs, coupled with molecular modeling, to produce a validated model of the binding mode of the subtype-selective antagonist A438079 at an intersubunit allosteric site. Within the allosteric site large effects on antagonist action were found for point mutants of residues F88A, D92A, F95A, and F103A that were conserved or similar between sensitive/insensitive P2XR subtypes, suggesting that these side-chain interactions were not solely responsible for high-affinity antagonist binding. Antagonist sensitivity was increased with mutations that remove the bulk of side chains around the center of the binding pocket, suggesting that the dimensions of the pocket make a significant contribution to selectivity. Chimeric receptors swapping the left flipper (around the orthosteric site) reduced both ATP and antagonist sensitivity. Point mutations within this region highlighted the contribution of a P2X7R-specific aspartic acid residue (D280) that modeling suggests forms a salt bridge with the lower body region of the receptor. The D280A mutant removing this charge increased ATP potency 15-fold providing a new insight into the low ATP sensitivity of the P2X7R. The ortho- and allosteric binding sites form either side of the β-strand Y291-E301 adjacent to the left flipper. This structural linking may explain the contribution of the left flipper to both agonist and antagonist action.
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Affiliation(s)
- Rebecca C Allsopp
- Department of Molecular and Cell Biology (R.C.A., S.D., A.B.D., R.S., R.J.E.) and Leicester Institute of Structural and Chemical Biology (R.S.), University of Leicester, Leicester, United Kingdom; and Department of Chemistry, College of Science, University of Baghdad, Baghdad, Iraq (S.D.)
| | - Sudad Dayl
- Department of Molecular and Cell Biology (R.C.A., S.D., A.B.D., R.S., R.J.E.) and Leicester Institute of Structural and Chemical Biology (R.S.), University of Leicester, Leicester, United Kingdom; and Department of Chemistry, College of Science, University of Baghdad, Baghdad, Iraq (S.D.)
| | - Anfal Bin Dayel
- Department of Molecular and Cell Biology (R.C.A., S.D., A.B.D., R.S., R.J.E.) and Leicester Institute of Structural and Chemical Biology (R.S.), University of Leicester, Leicester, United Kingdom; and Department of Chemistry, College of Science, University of Baghdad, Baghdad, Iraq (S.D.)
| | - Ralf Schmid
- Department of Molecular and Cell Biology (R.C.A., S.D., A.B.D., R.S., R.J.E.) and Leicester Institute of Structural and Chemical Biology (R.S.), University of Leicester, Leicester, United Kingdom; and Department of Chemistry, College of Science, University of Baghdad, Baghdad, Iraq (S.D.)
| | - Richard J Evans
- Department of Molecular and Cell Biology (R.C.A., S.D., A.B.D., R.S., R.J.E.) and Leicester Institute of Structural and Chemical Biology (R.S.), University of Leicester, Leicester, United Kingdom; and Department of Chemistry, College of Science, University of Baghdad, Baghdad, Iraq (S.D.)
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Ke Q, Ye J, Tang S, Wang J, Luo B, Ji F, Zhang X, Yu Y, Cheng X, Li Y. N1366S mutation of human skeletal muscle sodium channel causes paramyotonia congenita. J Physiol 2017; 595:6837-6850. [PMID: 28940424 DOI: 10.1113/jp274877] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/15/2017] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Paramyotonia congenita is a hereditary channelopathy caused by missense mutations in the SCN4A gene, which encodes the α subunit of the human skeletal muscle voltage-gated sodium channel NaV1.4. Affected individuals suffered from myotonia and paralysis of muscles, which were aggravated by exposure to cold. We report a three-generation Chinese family with patients presenting paramyotonia congenita and identify a novel N1366S mutation of NaV1.4. Whole-cell electrophysiological recordings of the N1366S channel reveal a gain-of-function change of gating in response to cold. Modelling and molecular dynamic simulation data suggest that an arginine-to-serine substitution at position 1366 increases the distance from N1366 to R1454 and disrupts the hydrogen bond formed between them at low temperature. We demonstrate that N1366S is a disease-causing mutation and that the temperature-sensitive alteration of N1366S channel activity may be responsible for the pronounced paramyotonia congenita symptoms of these patients. ABSTRACT Paramyotonia congenita is an autosomal dominant skeletal muscle channelopathy caused by missense mutations in SCN4A, the gene encoding the α subunit of the human skeletal muscle voltage-gated sodium channel NaV1.4. We report a three-generation family in which six members present clinical symptoms of paramyotonia congenita characterized by a marked worsening of myotonia by cold and by the presence of clear episodes of paralysis. We identified a novel mutation in SCN4A (Asn1366Ser, N1366S) in all patients in the family but not in healthy relatives or in 500 normal control subjects. Functional analysis of the channel protein expressed in HEK293 cells by whole-cell patch clamp recording revealed that the N1366S mutation led to significant alterations in the gating process of the NaV1.4 channel. The N1366S mutant displayed a cold-induced hyperpolarizing shift in the voltage dependence of activation and a depolarizing shift in fast inactivation, as well as a reduced rate of fast inactivation and accelerated recovery from fast inactivation. In addition, homology modelling and molecular dynamic simulation of N1366S and wild-type NaV1.4 channels indicated that the arginine-to-serine substitution disrupted the hydrogen bond formed between N1366 and R1454. Together, our results suggest that N1366S is a gain-of-function mutation of NaV1.4 at low temperature and the mutation may be responsible for the clinical symptoms of paramyotonia congenita in the affected family and constitute a basis for studies into its pathogenesis.
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Affiliation(s)
- Qing Ke
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jia Ye
- Department of Physiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Tissue Engineering and Regenerative Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Siyang Tang
- Department of Physiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Tissue Engineering and Regenerative Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jin Wang
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Benyan Luo
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Fang Ji
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xu Zhang
- Bejing Epigen Medical Institute, Beijing, China
| | - Ye Yu
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoyang Cheng
- Department of Anatomy, Histology and Embryology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuezhou Li
- Department of Physiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Tissue Engineering and Regenerative Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
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24
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Kasuya G, Yamaura T, Ma XB, Nakamura R, Takemoto M, Nagumo H, Tanaka E, Dohmae N, Nakane T, Yu Y, Ishitani R, Matsuzaki O, Hattori M, Nureki O. Structural insights into the competitive inhibition of the ATP-gated P2X receptor channel. Nat Commun 2017; 8:876. [PMID: 29026074 DOI: 10.1038/s41467-017-00887-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 08/02/2017] [Indexed: 12/29/2022] Open
Abstract
P2X receptors are non-selective cation channels gated by extracellular ATP, and the P2X7 receptor subtype plays a crucial role in the immune and nervous systems. Altered expression and dysfunctions of P2X7 receptors caused by genetic deletions, mutations, and polymorphic variations have been linked to various diseases, such as rheumatoid arthritis and hypertension. Despite the availability of crystal structures of P2X receptors, the mechanism of competitive antagonist action for P2X receptors remains controversial. Here, we determine the crystal structure of the chicken P2X7 receptor in complex with the competitive P2X antagonist, TNP-ATP. The structure reveals an expanded, incompletely activated conformation of the channel, and identified the unique recognition manner of TNP-ATP, which is distinct from that observed in the previously determined human P2X3 receptor structure. A structure-based computational analysis furnishes mechanistic insights into the TNP-ATP-dependent inhibition. Our work provides structural insights into the functional mechanism of the P2X competitive antagonist. P2X receptors are nonselective cation channels that are gated by extracellular ATP. Here the authors present the crystal structure of chicken P2X7 with its bound competitive antagonist TNP-ATP and give mechanistic insights into TNP-ATP dependent inhibition through further computational analysis and electrophysiology measurements.
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25
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Ishchenko Y, Novosolova N, Khafizov K, Bart G, Timonina A, Fayuk D, Skorinkin A, Giniatullin R. Reconstructed Serine 288 in the Left Flipper Region of the Rat P2X7 Receptor Stabilizes Nonsensitized States. Biochemistry 2017; 56:3394-3402. [PMID: 28616989 DOI: 10.1021/acs.biochem.7b00258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Serine 275, a conserved residue of the left flipper region of ATP-gated P2X3 receptors, plays a key role in both agonist binding and receptor desensitization. It is conserved in most of the P2X receptors except P2X7 and P2X6. By combining experimental patch-clamp and modeling approaches, we explored the role of the corresponding residue in the rat P2X7 receptor (rP2X7) by replacing the phenylalanine at position 288 with serine and characterizing the membrane currents generated by either the wild-type (WT) or the mutated rP2X7 receptor. F288S, an rP2X7 mutation, slowed the deactivation subsequent to 2 and 20 s applications of 1 mM ATP. F288S also prevented sensitization (a progressive current growth) observed with the WT in response to a 20 s application of 1 mM ATP. Increasing the ATP concentration to 5 mM promoted sensitization also in the mutated rP2X7 receptor, accelerating the deactivation rate to typical WT values. YO-PRO1 uptake in cells expressing either the WT or the F288S P2X7 receptor was consistent with recorded membrane current data. Interestingly, in the human P2X7 (hP2X7) receptor, substitution Y288S did not change the deactivation rate, while the Y288F mutant generated a "rat-like" phenotype with a fast deactivation rate. Our combined experimental, kinetic, and molecular modeling data suggest that the rat F288S novel phenotype is due to a slower rate of ATP binding and/or unbinding and stabilization of nonsensitized receptor states.
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Affiliation(s)
| | | | - Kamil Khafizov
- Moscow Institute of Physics and Technology , Dolgoprudny, Moscow Region, Russian Federation.,Central Research Institute of Epidemiology , Moscow, Russian Federation
| | - Geneviève Bart
- A. I. Virtanen Institute, University of Eastern Finland , Kuopio, Finland.,Faculty of Biochemistry and Molecular Medicine, University of Oulu , Oulu, Finland
| | - Arina Timonina
- A. I. Virtanen Institute, University of Eastern Finland , Kuopio, Finland
| | - Dmitriy Fayuk
- A. I. Virtanen Institute, University of Eastern Finland , Kuopio, Finland
| | - Andrei Skorinkin
- Department of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences , Kazan, Russian Federation.,Lab of Neuropharmacology, Kazan Federal University , Kazan, Russian Federation
| | - Rashid Giniatullin
- A. I. Virtanen Institute, University of Eastern Finland , Kuopio, Finland.,Lab of Neurobiology, Kazan Federal University , Kazan, Russian Federation
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26
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Kasuya G, Fujiwara Y, Tsukamoto H, Morinaga S, Ryu S, Touhara K, Ishitani R, Furutani Y, Hattori M, Nureki O. Structural insights into the nucleotide base specificity of P2X receptors. Sci Rep 2017; 7:45208. [PMID: 28332633 PMCID: PMC5362899 DOI: 10.1038/srep45208] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 02/20/2017] [Indexed: 11/19/2022] Open
Abstract
P2X receptors are trimeric ATP-gated cation channels involved in diverse physiological processes, ranging from muscle contraction to nociception. Despite the recent structure determination of the ATP-bound P2X receptors, the molecular mechanism of the nucleotide base specificity has remained elusive. Here, we present the crystal structure of zebrafish P2X4 in complex with a weak affinity agonist, CTP, together with structure-based electrophysiological and spectroscopic analyses. The CTP-bound structure revealed a hydrogen bond, between the cytosine base and the side chain of the basic residue in the agonist binding site, which mediates the weak but significant affinity for CTP. The cytosine base is further recognized by two main chain atoms, as in the ATP-bound structure, but their bond lengths seem to be extended in the CTP-bound structure, also possibly contributing to the weaker affinity for CTP over ATP. This work provides the structural insights for the nucleotide base specificity of P2X receptors.
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Affiliation(s)
- Go Kasuya
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Yuichiro Fujiwara
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan
| | - Hisao Tsukamoto
- Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki, 444-8585, Japan
| | - Satoshi Morinaga
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Satoshi Ryu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Kazushige Touhara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Ryuichiro Ishitani
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Yuji Furutani
- Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki, 444-8585, Japan
| | - Motoyuki Hattori
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai, 200438, China
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
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27
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Wang J, Sun LF, Cui WW, Zhao WS, Ma XF, Li B, Liu Y, Yang Y, Hu YM, Huang LD, Cheng XY, Li L, Lu XY, Tian Y, Yu Y. Intersubunit physical couplings fostered by the left flipper domain facilitate channel opening of P2X4 receptors. J Biol Chem 2017; 292:7619-7635. [PMID: 28302727 DOI: 10.1074/jbc.m116.771121] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 03/03/2017] [Indexed: 12/14/2022] Open
Abstract
P2X receptors are ATP-gated trimeric channels with important roles in diverse pathophysiological functions. A detailed understanding of the mechanism underlying the gating process of these receptors is thus fundamentally important and may open new therapeutic avenues. The left flipper (LF) domain of the P2X receptors is a flexible loop structure, and its coordinated motions together with the dorsal fin (DF) domain are crucial for the channel gating of the P2X receptors. However, the mechanism underlying the crucial role of the LF domain in the channel gating remains obscure. Here, we propose that the ATP-induced allosteric changes of the LF domain enable it to foster intersubunit physical couplings among the DF and two lower body domains, which are pivotal for the channel gating of P2X4 receptors. Metadynamics analysis indicated that these newly established intersubunit couplings correlate well with the ATP-bound open state of the receptors. Moreover, weakening or strengthening these physical interactions with engineered intersubunit metal bridges remarkably decreased or increased the open probability of the receptors, respectively. Further disulfide cross-linking and covalent modification confirmed that the intersubunit physical couplings among the DF and two lower body domains fostered by the LF domain at the open state act as an integrated structural element that is stringently required for the channel gating of P2X4 receptors. Our observations provide new mechanistic insights into P2X receptor activation and will stimulate development of new allosteric modulators of P2X receptors.
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Affiliation(s)
- Jin Wang
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Liang-Fei Sun
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wen-Wen Cui
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wen-Shan Zhao
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xue-Fei Ma
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.,the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China, and
| | - Bin Li
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.,the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China, and
| | - Yan Liu
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yang Yang
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - You-Min Hu
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Li-Dong Huang
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiao-Yang Cheng
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Lingyong Li
- the Department of Anesthesiology and Perioperative Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Xiang-Yang Lu
- the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China, and
| | - Yun Tian
- the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China, and
| | - Ye Yu
- From the Department of Pharmacology and Chemical Biology, Institute of Medical Sciences and Hongqiao International Institute of Medicine of Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China, .,the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China, and
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28
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Abdelrahman A, Namasivayam V, Hinz S, Schiedel AC, Köse M, Burton M, El-Tayeb A, Gillard M, Bajorath J, de Ryck M, Müller CE. Characterization of P2X4 receptor agonists and antagonists by calcium influx and radioligand binding studies. Biochem Pharmacol 2017; 125:41-54. [DOI: 10.1016/j.bcp.2016.11.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 11/15/2016] [Indexed: 10/20/2022]
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29
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Zhang L, Wang J, Xu A, Zhong C, Lu W, Deng L, Li R. A Rationally Designed TNF-α Epitope-Scaffold Immunogen Induces Sustained Antibody Response and Alleviates Collagen-Induced Arthritis in Mice. PLoS One 2016; 11:e0163080. [PMID: 27658047 DOI: 10.1371/journal.pone.0163080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 09/04/2016] [Indexed: 12/29/2022] Open
Abstract
The TNF-α biological inhibitors have significantly improved the clinical outcomes of many autoimmune diseases, in particular rheumatoid arthritis. However, the practical uses are limited due to high costs and the risk of anti-drug antibody responses. Attempts to develop anti-TNF-α vaccines have generated encouraging data in animal models, however, data from clinical trials have not met expectations. In present study, we designed a TNF-α epitope-scaffold immunogen DTNF7 using the transmembrane domain of diphtheria toxin, named DTT as a scaffold. Molecular dynamics simulation shows that the grafted TNF-α epitope is entirely surface-exposed and presented in a native-like conformation while the rigid helical structure of DTT is minimally perturbed, thereby rendering the immunogen highly stable. Immunization of mice with alum formulated DTNF7 induced humoral responses against native TNF-α, and the antibody titer was sustained for more than 6 months, which supports a role of the universal CD4 T cell epitopes of DTT in breaking self-immune tolerance. In a mouse model of rheumatoid arthritis, DTNF7-alum vaccination markedly delayed the onset of collagen-induced arthritis, and reduced incidence as well as clinical score. DTT is presumed safe as an epitope carrier because a catalytic inactive mutant of diphtheria toxin, CRM197 has good clinical safety records as an active vaccine component. Taken all together, we show that DTT-based epitope vaccine is a promising strategy for prevention and treatment of autoimmune diseases.
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30
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Lu W, Qiu L, Yan Z, Lin Z, Cao M, Hu C, Wang Z, Wang J, Yu Y, Cheng X, Cao P, Li R. Cytotoxic T cell responses are enhanced by antigen design involving the presentation of MUC1 peptide on cholera toxin B subunit. Oncotarget 2016; 6:34537-48. [PMID: 26417929 PMCID: PMC4741471 DOI: 10.18632/oncotarget.5307] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 09/08/2015] [Indexed: 11/25/2022] Open
Abstract
Induction of cytotoxic T lymphocytes (CTL) is critical to cancer vaccine based immunotherapy. Efforts to elicit CTLs against tumor MUC1 with peptide based vaccine have not been successful in clinical application. We have design a MUC1 vaccine by replacing B cell epitope of CTB with MUC1 VNTR peptide. Immunization with hybrid CTB-MUC1 plus aluminum hydroxide and CpG adujuvant (CTB-MUC1-Alum-CpG) induce MUC1-specific CTLs in mice. Moreover, this vaccination can prevent tumor growth and reduce tumor burden in MUC1+B16 mice model. Meanwhile, CTB-MUC1-Alum-CpG vaccination can promote Th1 cells and CD8+ T cells inflate to tumor tissue. Our approach might be applicable to other cancer vaccine design.
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Affiliation(s)
- Wuguang Lu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.,Laboratory of Cellular and Molecular Biology, Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210028, China.,Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing 210028, China
| | - Lingchong Qiu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zhanpeng Yan
- Laboratory of Cellular and Molecular Biology, Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210028, China.,Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing 210028, China
| | - Zhibing Lin
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Meng Cao
- Laboratory of Cellular and Molecular Biology, Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210028, China.,Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing 210028, China
| | - Chunping Hu
- Laboratory of Cellular and Molecular Biology, Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210028, China.,Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing 210028, China
| | - Zhigang Wang
- Laboratory of Cellular and Molecular Biology, Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210028, China.,Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing 210028, China
| | - Jin Wang
- Institute of Medical Science and Department of Pharmacology and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China
| | - Ye Yu
- Institute of Medical Science and Department of Pharmacology and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China
| | - Xiaoyang Cheng
- Institute of Medical Science and Department of Pharmacology and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China
| | - Peng Cao
- Laboratory of Cellular and Molecular Biology, Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210028, China.,Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing 210028, China
| | - Rongxiu Li
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.,Engineering Research Center of Cell & Therapeutic Antibody, Ministry of Education, School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China
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Niu YY, Yang Y, Liu Y, Huang LD, Yang XN, Fan YZ, Cheng XY, Cao P, Hu YM, Li L, Lu XY, Tian Y, Yu Y. Exploration of the Peptide Recognition of an Amiloride-sensitive FMRFamide Peptide-gated Sodium Channel. J Biol Chem 2016; 291:7571-82. [PMID: 26867576 DOI: 10.1074/jbc.m115.710251] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Indexed: 12/22/2022] Open
Abstract
FMRFamide (Phe-Met-Arg-Phe-NH2)-activated sodium channel (FaNaC) is an amiloride-sensitive sodium channel activated by endogenous tetrapeptide in invertebrates, and belongs to the epithelial sodium channel/degenerin (ENaC/DEG) superfamily. The ENaC/DEG superfamily differs markedly in its means of activation, such as spontaneously opening or gating by mechanical stimuli or tissue acidosis. Recently, it has been observed that a number of ENaC/DEG channels can be activated by small molecules or peptides, indicating that the ligand-gating may be an important feature of this superfamily. The peptide ligand control of the channel gating might be an ancient ligand-gating feature in this superfamily. Therefore, studying the peptide recognition of FaNaC channels would advance our understanding of the ligand-gating properties of this superfamily of ion channels. Here we demonstrate that Tyr-131, Asn-134, Asp-154, and Ile-160, located in the putative upper finger domain ofHelix aspersaFaNaC (HaFaNaC) channels, are key residues for peptide recognition of this ion channel. Two HaFaNaC specific-insertion motifs among the ENaC/DEG superfamily, residing at the putative α4-α5 linker of the upper thumb domain and the α6-α7 linker of the upper knuckle domain, are also essential for the peptide recognition of HaFaNaC channels. Chemical modifications and double mutant cycle analysis further indicated that those two specific inserts and key residues in the upper finger domain together participate in peptide recognition of HaFaNaC channels. This ligand recognition site is distinct from that of acid-sensing ion channels (ASICs) by a longer distance between the recognition site and the channel gate, carrying useful information about the ligand gating and the evolution of the trimeric ENaC/DEG superfamily of ion channels.
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Affiliation(s)
- You-Ya Niu
- From the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China, Institute of Medical Sciences and Departments of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yang Yang
- Institute of Medical Sciences and Departments of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yan Liu
- Institute of Medical Sciences and Departments of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Li-Dong Huang
- Institute of Medical Sciences and Departments of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiao-Na Yang
- From the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China, Institute of Medical Sciences and Departments of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ying-Zhe Fan
- Putuo District Center Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai, 200062, China
| | - Xiao-Yang Cheng
- Institute of Medical Sciences and Departments of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Peng Cao
- Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China, and Laboratory of Cellular and Molecular Biology, Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing 210028, China
| | - You-Min Hu
- Institute of Medical Sciences and Departments of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Lingyong Li
- Department of Anesthesiology and Perioperative Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Xiang-Yang Lu
- From the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China
| | - Yun Tian
- From the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China,
| | - Ye Yu
- From the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China, Institute of Medical Sciences and Departments of Pharmacology and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China,
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32
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Zhao WS, Sun MY, Sun LF, Liu Y, Yang Y, Huang LD, Fan YZ, Cheng XY, Cao P, Hu YM, Li L, Tian Y, Wang R, Yu Y. A Highly Conserved Salt Bridge Stabilizes the Kinked Conformation of β2,3-Sheet Essential for Channel Function of P2X4 Receptors. J Biol Chem 2016; 291:7990-8003. [PMID: 26865631 DOI: 10.1074/jbc.m115.711127] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Indexed: 01/01/2023] Open
Abstract
Significant progress has been made in understanding the roles of crucial residues/motifs in the channel function of P2X receptors during the pre-structure era. The recent structural determination of P2X receptors allows us to reevaluate the role of those residues/motifs. Residues Arg-309 and Asp-85 (rat P2X4 numbering) are highly conserved throughout the P2X family and were involved in loss-of-function polymorphism in human P2X receptors. Previous studies proposed that they participated in direct ATP binding. However, the crystal structure of P2X demonstrated that those two residues form an intersubunit salt bridge located far away from the ATP-binding site. Therefore, it is necessary to reevaluate the role of this salt bridge in P2X receptors. Here, we suggest the crucial role of this structural element both in protein stability and in channel gating rather than direct ATP interaction and channel assembly. Combining mutagenesis, charge swap, and disulfide cross-linking, we revealed the stringent requirement of this salt bridge in normal P2X4 channel function. This salt bridge may contribute to stabilizing the bending conformation of the β2,3-sheet that is structurally coupled with this salt bridge and the α2-helix. Strongly kinked β2,3 is essential for domain-domain interactions between head domain, dorsal fin domain, right flipper domain, and loop β7,8 in P2X4 receptors. Disulfide cross-linking with directions opposing or along the bending angle of the β2,3-sheet toward the α2-helix led to loss-of-function and gain-of-function of P2X4 receptors, respectively. Further insertion of amino acids with bulky side chains into the linker between the β2,3-sheet or the conformational change of the α2-helix, interfering with the kinked conformation of β2,3, led to loss-of-function of P2X4 receptors. All these findings provided new insights in understanding the contribution of the salt bridge between Asp-85 and Arg-309 and its structurally coupled β2,3-sheet to the function of P2X receptors.
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Affiliation(s)
- Wen-Shan Zhao
- From the School of Life Sciences and Key Laboratory of Preclinical Study for New Drugs of Gansu Province School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China, the Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Meng-Yang Sun
- From the School of Life Sciences and Key Laboratory of Preclinical Study for New Drugs of Gansu Province School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China, the Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Liang-Fei Sun
- the Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yan Liu
- the Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yang Yang
- the Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Li-Dong Huang
- the Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ying-Zhe Fan
- the Putuo District Center Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai 200062, China
| | - Xiao-Yang Cheng
- the Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Peng Cao
- the Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China, and the Laboratory of Cellular and Molecular Biology, Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing 210028, China
| | - You-Min Hu
- the Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Lingyong Li
- the Department of Anesthesiology and Perioperative Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Yun Tian
- the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
| | - Rui Wang
- From the School of Life Sciences and Key Laboratory of Preclinical Study for New Drugs of Gansu Province School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China,
| | - Ye Yu
- the Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China, the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China,
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Habermacher C, Martz A, Calimet N, Lemoine D, Peverini L, Specht A, Cecchini M, Grutter T. Photo-switchable tweezers illuminate pore-opening motions of an ATP-gated P2X ion channel. eLife 2016; 5:e11050. [PMID: 26808983 PMCID: PMC4739762 DOI: 10.7554/elife.11050] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 10/27/2015] [Indexed: 11/13/2022] Open
Abstract
P2X receptors function by opening a transmembrane pore in response to extracellular ATP. Recent crystal structures solved in apo and ATP-bound states revealed molecular motions of the extracellular domain following agonist binding. However, the mechanism of pore opening still remains controversial. Here we use photo-switchable cross-linkers as ‘molecular tweezers’ to monitor a series of inter-residue distances in the transmembrane domain of the P2X2 receptor during activation. These experimentally based structural constraints combined with computational studies provide high-resolution models of the channel in the open and closed states. We show that the extent of the outer pore expansion is significantly reduced compared to the ATP-bound structure. Our data further reveal that the inner and outer ends of adjacent pore-lining helices come closer during opening, likely through a hinge-bending motion. These results provide new insight into the gating mechanism of P2X receptors and establish a versatile strategy applicable to other membrane proteins. DOI:http://dx.doi.org/10.7554/eLife.11050.001 Protein receptors in the cell membrane play an important role transmitting signals from outside to inside the cell. Members of the P2X family of receptors are ion channels that form pores through the membrane. When a molecule of ATP binds to the external region of the receptor, it activates it and causes the receptor to change from a closed to an open shape. Once opened, ions flow through the channel’s pore and trigger a response inside the cell. P2X receptors are found on most animal cells (including nerve cells) and are involved in both normal cellular activity and processes linked to disease, including inflammation and chronic pain. The P2X receptor has three parts or subunits, and each contributes to the channel’s pore. Recent research using a technique called X-ray crystallography has revealed how ATP binding causes shape changes in the external region of the receptor. But these three-dimensional structures did not reveal details of how the subunits move to open or close the channel’s pore. Habermacher et al. have now added light-sensitive linkers onto the P2X receptor in a way that meant that different colors of light could be used to force parts of the receptor to come closer together or move apart. This allowed the pore to be opened and closed in response to changes in light. Habermacher et al. then studied the behavior of these modified receptors within a natural membrane and found that the light stimulated movements were similar to those seen with ATP. When the behavior of the receptor and light-sensitive linkers was studied using computer simulations, it led to new models of the P2X pore in the open and closed state. In these models, the open channel was more tightly packed than in the previous structure and an unexpected hinge-bending movement was seen to accompany the opening of the channel. It is hoped that this new approach will also be useful for probing how other membrane proteins change their shape when activated. DOI:http://dx.doi.org/10.7554/eLife.11050.002
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Affiliation(s)
- Chloé Habermacher
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Adeline Martz
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Nicolas Calimet
- ISIS, Unité Mixte de Recherche 7006, Laboratoire d'Ingénierie des Fonctions Moléculaires, Strasbourg, France
| | - Damien Lemoine
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Laurie Peverini
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Alexandre Specht
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Marco Cecchini
- ISIS, Unité Mixte de Recherche 7006, Laboratoire d'Ingénierie des Fonctions Moléculaires, Strasbourg, France
| | - Thomas Grutter
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
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34
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Kasuya G, Fujiwara Y, Takemoto M, Dohmae N, Nakada-Nakura Y, Ishitani R, Hattori M, Nureki O. Structural Insights into Divalent Cation Modulations of ATP-Gated P2X Receptor Channels. Cell Rep 2016; 14:932-44. [PMID: 26804916 DOI: 10.1016/j.celrep.2015.12.087] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 11/03/2015] [Accepted: 12/18/2015] [Indexed: 02/03/2023] Open
Abstract
P2X receptors are trimeric ATP-gated cation channels involved in physiological processes ranging widely from neurotransmission to pain and taste signal transduction. The modulation of the channel gating, including that by divalent cations, contributes to these diverse physiological functions of P2X receptors. Here, we report the crystal structure of an invertebrate P2X receptor from the Gulf Coast tick Amblyomma maculatum in the presence of ATP and Zn(2+) ion, together with electrophysiological and computational analyses. The structure revealed two distinct metal binding sites, M1 and M2, in the extracellular region. The M1 site, located at the trimer interface, is responsible for Zn(2+) potentiation by facilitating the structural change of the extracellular domain for pore opening. In contrast, the M2 site, coupled with the ATP binding site, might contribute to regulation by Mg(2+). Overall, our work provides structural insights into the divalent cation modulations of P2X receptors.
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Wang J, Yu Y. Insights into the channel gating of P2X receptors from structures, dynamics and small molecules. Acta Pharmacol Sin 2016; 37:44-55. [PMID: 26725734 DOI: 10.1038/aps.2015.127] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/02/2015] [Indexed: 12/16/2022] Open
Abstract
P2X receptors, as ATP-gated non-selective trimeric ion channels, are permeable to Na(+), K(+) and Ca(2+). Comparing with other ligand-gated ion channel families, P2X receptors are distinct in their unique gating properties and pathophysiological roles, and have attracted attention as promising drug targets for a variety of diseases, such as neuropathic pain, multiple sclerosis, rheumatoid arthritis and thrombus. Several small molecule inhibitors for distinct P2X subtypes have entered into clinical trials. However, many questions regarding the gating mechanism of P2X remain unsolved. The structural determinations of P2X receptors at the resting and ATP-bound open states revealed that P2X receptor gating is a cooperative allosteric process involving multiple domains, which marks the beginning of the post-structure era of P2X research at atomic level. Here, we review the current knowledge on the structure-function relationship of P2X receptors, depict the whole picture of allosteric changes during the channel gating, and summarize the active sites that may contribute to new strategies for developing novel allosteric drugs targeting P2X receptors.
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36
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Hausmann R, Kless A, Schmalzing G. Key sites for P2X receptor function and multimerization: overview of mutagenesis studies on a structural basis. Curr Med Chem 2015; 22:799-818. [PMID: 25439586 PMCID: PMC4460280 DOI: 10.2174/0929867322666141128163215] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 10/20/2014] [Accepted: 11/27/2014] [Indexed: 02/07/2023]
Abstract
P2X receptors constitute a seven-member family (P2X1-7) of extracellular ATP-gated cation
channels of widespread expression. Because P2X receptors have been implicated in neurological, inflammatory
and cardiovascular diseases, they constitute promising drug targets. Since the first P2X cDNA sequences
became available in 1994, numerous site-directed mutagenesis studies have been conducted to disclose
key sites of P2X receptor function and oligomerization. The publication of the 3-Å crystal structures of the zebrafish
P2X4 (zfP2X4) receptor in the homotrimeric apo-closed and ATP-bound open states in 2009 and 2012, respectively, has
ushered a new era by allowing for the interpretation of the wealth of molecular data in terms of specific three-dimensional
models and by paving the way for designing more-decisive experiments. Thanks to these structures, the last five years
have provided invaluable insight into our understanding of the structure and function of the P2X receptor class of ligandgated
ion channels. In this review, we provide an overview of mutagenesis studies of the pre- and post-crystal structure
eras that identified amino acid residues of key importance for ligand binding, channel gating, ion flow, formation of the
pore and the channel gate, and desensitization. In addition, the sites that are involved in the trimerization of P2X receptors
are reviewed based on mutagenesis studies and interface contacts that were predicted by the zfP2X4 crystal structures.
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Affiliation(s)
| | | | - Gunther Schmalzing
- Department of Molecular Pharmacology, Medical Faculty of the RWTH Aachen University, Wendlingweg 2, D-52074 Aachen, Germany.
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37
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Habermacher C, Dunning K, Chataigneau T, Grutter T. Molecular structure and function of P2X receptors. Neuropharmacology 2015; 104:18-30. [PMID: 26231831 DOI: 10.1016/j.neuropharm.2015.07.032] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 07/23/2015] [Accepted: 07/26/2015] [Indexed: 12/22/2022]
Abstract
ATP-gated P2X receptors are trimeric ion channels selective to cations. Recent progress in the molecular biophysics of these channels enables a better understanding of their function. In particular, data obtained from biochemical, electrophysiogical and molecular engineering in the light of recent X-ray structures now allow delineation of the principles of ligand binding, channel opening and allosteric modulation. However, although a picture emerges as to how ATP triggers channel opening, there are a number of intriguing questions that remain to be answered, in particular how the pore itself opens in response to ATP and how the intracellular domain, for which structural information is limited, moves during activation. In this review, we provide a summary of functional studies in the context of the post-structure era, aiming to clarify our understanding of the way in which P2X receptors function in response to ATP binding, as well as the mechanism by which allosteric modulators are able to regulate receptor function. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Affiliation(s)
- Chloé Habermacher
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, F-67400, Illkirch, France; Université de Strasbourg, Faculté de Pharmacie, F-67400, Illkirch, France
| | - Kate Dunning
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, F-67400, Illkirch, France; Université de Strasbourg, Faculté de Pharmacie, F-67400, Illkirch, France
| | - Thierry Chataigneau
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, F-67400, Illkirch, France; Université de Strasbourg, Faculté de Pharmacie, F-67400, Illkirch, France
| | - Thomas Grutter
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, F-67400, Illkirch, France; Université de Strasbourg, Faculté de Pharmacie, F-67400, Illkirch, France.
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38
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Tvrdonova V, Rokic MB, Stojilkovic SS, Zemkova H. Identification of functionally important residues of the rat P2X4 receptor by alanine scanning mutagenesis of the dorsal fin and left flipper domains. PLoS One 2014; 9:e112902. [PMID: 25398027 PMCID: PMC4232510 DOI: 10.1371/journal.pone.0112902] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/16/2014] [Indexed: 12/01/2022] Open
Abstract
Crystallization of the zebrafish P2X4 receptor in both open and closed states revealed conformational differences in the ectodomain structures, including the dorsal fin and left flipper domains. Here, we focused on the role of these domains in receptor activation, responsiveness to orthosteric ATP analogue agonists, and desensitization. Alanine scanning mutagenesis of the R203-L214 (dorsal fin) and the D280-N293 (left flipper) sequences of the rat P2X4 receptor showed that ATP potency/efficacy was reduced in 15 out of 26 alanine mutants. The R203A, N204A, and N293A mutants were essentially non-functional, but receptor function was restored by ivermectin, an allosteric modulator. The I205A, T210A, L214A, P290A, G291A, and Y292A mutants exhibited significant changes in the responsiveness to orthosteric analog agonists 2-(methylthio)adenosine 5′-triphosphate, adenosine 5′-(γ-thio)triphosphate, 2′(3′-O-(4-benzoylbenzoyl)adenosine 5′-triphosphate, and α,β-methyleneadenosine 5′-triphosphate. In contrast, the responsiveness of L206A, N208A, D280A, T281A, R282A, and H286A mutants to analog agonists was comparable to that of the wild type receptor. Among these mutants, D280A, T281A, R282A, H286A, G291A, and Y292A also exhibited increased time-constant of the desensitizing current response. These experiments, together with homology modeling, indicate that residues located in the upper part of the dorsal fin and left flipper domains, relative to distance from the channel pore, contribute to the organization of the ATP binding pocket and to the initiation of signal transmission towards residues in the lower part of both domains. The R203 and N204 residues, deeply buried in the protein, may integrate the output signal from these two domains towards the gate. In addition, the left flipper residues predominantly account for the control of transition of channels from an open to a desensitized state.
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Affiliation(s)
- Vendula Tvrdonova
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Department of Physiology of Animals, Faculty of Science, Charles University, Prague, Czech Republic
| | - Milos B. Rokic
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Section on Cellular Signaling, Program in Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Stanko S. Stojilkovic
- Section on Cellular Signaling, Program in Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hana Zemkova
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
- * E-mail:
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