1
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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] [Abstract] [Key Words] [MESH Headings] [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, China; School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Ting-Ting Wang
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Wen-Hui Wang
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Li Guan
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Chang-Run Guo
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Xing-Hua Li
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Yun-Tao Lei
- School 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 Traditional Chinese Medicine, Shanghai, China
| | - Xiao-Na Yang
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 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
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Ye Yu
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China.
| | - Yun Tian
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China.
| | - Jin Wang
- School of Basic Medicine and Clinical Pharmacy and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China.
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2
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Xu Y, Chen F. Factors and Molecular Mechanisms Influencing the Protein Synthesis, Degradation and Membrane Trafficking of ASIC1a. Front Cell Dev Biol 2020; 8:596304. [PMID: 33195276 PMCID: PMC7644914 DOI: 10.3389/fcell.2020.596304] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 10/05/2020] [Indexed: 12/31/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are members of the degenerin/epithelial sodium channel superfamily. They are extracellular pH sensors that are activated by protons. Among all ASICs, ASIC1a is one of the most intensively studied isoforms because of its unique ability to be permeable to Ca2+. In addition, it is considered to contribute to various pathophysiological conditions. As a membrane proton receptor, the number of ASIC1a present on the cell surface determines its physiological and pathological functions, and this number partially depends on protein synthesis, degradation, and membrane trafficking processes. Recently, several studies have shown that various factors affect these processes. Therefore, this review elucidated the major factors and underlying molecular mechanisms affecting ASIC1a protein expression and membrane trafficking.
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Affiliation(s)
- Yayun Xu
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, China.,The Key Laboratory of Major Autoimmune Diseases of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China.,The Key Laboratory of Anti-inflammatory and Immune Medicines, Ministry of Education, Hefei, China
| | - Feihu Chen
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, China.,The Key Laboratory of Major Autoimmune Diseases of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China.,The Key Laboratory of Anti-inflammatory and Immune Medicines, Ministry of Education, Hefei, China
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3
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Rook ML, Musgaard M, MacLean DM. Coupling structure with function in acid-sensing ion channels: challenges in pursuit of proton sensors. J Physiol 2020; 599:417-430. [PMID: 32306405 DOI: 10.1113/jp278707] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/27/2020] [Indexed: 12/25/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are a class of trimeric cation-selective ion channels activated by changes in pH within the physiological range. They are widely expressed in the central and peripheral nervous systems where they participate in a range of physiological and pathophysiological situations such as learning and memory, pain sensation, fear and anxiety, substance abuse and cell death. ASICs are localized to cell bodies and dendrites, including the postsynaptic density, and within the last 5 years several examples of proton-evoked ASIC excitatory postsynaptic currents have emerged. Thus, ASICs have become bona fide neurotransmitter-gated ion channels, activated by the smallest neurotransmitter possible: protons. Here we review how protons are thought to drive the conformational changes associated with ASIC activation and desensitization. In particular, we weigh the evidence for and against the so-called 'acidic pocket' being a vital proton sensor and discuss the emerging role of the β11-12 linker as a desensitization switch or 'molecular clutch'. We also examine how proton-induced conformational changes pose unique challenges to classical molecular dynamics simulations, as well as some possible solutions. Given the emergence of new methodologies and structures, the coming years will probably see many advances in the study of acid-sensing ion channels.
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Affiliation(s)
- Matthew L Rook
- Graduate Program in Cellular and Molecular Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY, 14642, USA
| | - Maria Musgaard
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 75 Laurier Ave E, Ottawa, ON, K1N 6N5, Canada
| | - David M MacLean
- Department of Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY, 14642, USA
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4
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Agrawal PB, Wang R, Li HL, Schmitz-Abe K, Simone-Roach C, Chen J, Shi J, Louie T, Sheng S, Towne MC, Brainson CF, Matthay MA, Kim CF, Bamshad M, Emond MJ, Gerard NP, Kleyman TR, Gerard C. The Epithelial Sodium Channel Is a Modifier of the Long-Term Nonprogressive Phenotype Associated with F508del CFTR Mutations. Am J Respir Cell Mol Biol 2017; 57:711-720. [PMID: 28708422 PMCID: PMC5765421 DOI: 10.1165/rcmb.2017-0166oc] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 07/05/2017] [Indexed: 12/11/2022] Open
Abstract
Cystic fibrosis (CF) remains the most lethal genetic disease in the Caucasian population. However, there is great variability in clinical phenotypes and survival times, even among patients harboring the same genotype. We identified five patients with CF and a homozygous F508del mutation in the CFTR gene who were in their fifth or sixth decade of life and had shown minimal changes in lung function over a longitudinal period of more than 20 years. Because of the rarity of this long-term nonprogressive phenotype, we hypothesized these individuals may carry rare genetic variants in modifier genes that ameliorate disease severity. Individuals at the extremes of survival time and lung-function trajectory underwent whole-exome sequencing, and the sequencing data were filtered to include rare missense, stopgain, indel, and splicing variants present with a mean allele frequency of <0.2% in general population databases. Epithelial sodium channel (ENaC) mutants were generated via site-directed mutagenesis and expressed for Xenopus oocyte assays. Four of the five individuals carried extremely rare or never reported variants in the SCNN1D and SCNN1B genes of the ENaC. Separately, an independently enriched rare variant in SCNN1D was identified in the Exome Variant Server database associated with a milder pulmonary disease phenotype. Functional analysis using Xenopus oocytes revealed that two of the three variants in δ-ENaC encoded by SCNN1D exhibited hypomorphic channel activity. Our data suggest a potential role for δ-ENaC in controlling sodium reabsorption in the airways, and advance the plausibility of ENaC as a therapeutic target in CF.
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Affiliation(s)
- Pankaj B. Agrawal
- Divisions of Newborn Medicine
- Genetics and Genomics
- Gene Discovery Core, Manton Center for Orphan Disease Research
| | | | - Hongmei Lisa Li
- Stem Cell Program, Division of Hematology/Oncology, Boston Children’s Hospital, Boston, Massachusetts
- Harvard Stem Cell Institute, Cambridge, Massachusetts
- Department of Genetics, and
| | - Klaus Schmitz-Abe
- Genetics and Genomics
- Gene Discovery Core, Manton Center for Orphan Disease Research
| | | | | | - Jiahai Shi
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR
| | - Tin Louie
- Biostatistics and Center for Biomedical Statistics
| | | | - Meghan C. Towne
- Genetics and Genomics
- Gene Discovery Core, Manton Center for Orphan Disease Research
| | | | - Michael A. Matthay
- Departments of Medicine and
- Anesthesia, Cardiovascular Research Institute, University of California–San Francisco, San Francisco, California
| | - Carla F. Kim
- Pulmonary and Respiratory Diseases, and
- Stem Cell Program, Division of Hematology/Oncology, Boston Children’s Hospital, Boston, Massachusetts
- Harvard Stem Cell Institute, Cambridge, Massachusetts
- Department of Genetics, and
| | - Michael Bamshad
- Pediatrics and Genome Sciences, University of Washington, Seattle, Washington
| | | | - Norma P. Gerard
- Pulmonary and Respiratory Diseases, and
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Thomas R. Kleyman
- Departments of Medicine
- Cell Biology, and Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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5
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Yang XN, Niu YY, Liu Y, Yang Y, Wang J, Cheng XY, Liang H, Wang HS, Hu YM, Lu XY, Zhu MX, Xu TL, Tian Y, Yu Y. The nonproton ligand of acid-sensing ion channel 3 activates mollusk-specific FaNaC channels via a mechanism independent of the native FMRFamide peptide. J Biol Chem 2017; 292:21662-21675. [PMID: 29123030 DOI: 10.1074/jbc.m117.814707] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 11/07/2017] [Indexed: 12/13/2022] Open
Abstract
The degenerin/epithelial sodium channel (DEG/ENaC) superfamily of ion channels contains subfamilies with diverse functions that are fundamental to many physiological and pathological processes, ranging from synaptic transmission to epileptogenesis. The absence in mammals of some DEG/ENaCs subfamily orthologues such as FMRFamide peptide-activated sodium channels (FaNaCs), which have been identified only in mollusks, indicates that the various subfamilies diverged early in evolution. We recently reported that the nonproton agonist 2-guanidine-4-methylquinazoline (GMQ) activates acid-sensing ion channels (ASICs), a DEG/ENaC subfamily mainly in mammals, in the absence of acidosis. Here, we show that GMQ also could directly activate the mollusk-specific FaNaCs. Differences in ion selectivity and unitary conductance and effects of substitutions at key residues revealed that GMQ and FMRFamide activate FaNaCs via distinct mechanisms. The presence of two activation mechanisms in the FaNaC subfamily diverging early in the evolution of DEG/ENaCs suggested that dual gating is an ancient feature in this superfamily. Notably, the GMQ-gating mode is still preserved in the mammalian ASIC subfamily, whereas FMRFamide-mediated channel gating was lost during evolution. This implied that GMQ activation may be essential for the functions of mammalian DEG/ENaCs. Our findings provide new insights into the evolution of DEG/ENaCs and may facilitate the discovery and characterization of their endogenous agonists.
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Affiliation(s)
- Xiao-Na Yang
- From the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China.,Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - You-Ya Niu
- From the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China.,Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.,Department of Cell Biology and Genetics, Hunan University of Medicine, Huaihua, 418000, China
| | - Yan Liu
- Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yang Yang
- Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jin Wang
- Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiao-Yang Cheng
- Discipline of Neuroscience, Department of Anatomy, Histology, and Embryology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hong Liang
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmacy, Guangxi Normal University, Guilin, 541004, China, and
| | - 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, and
| | - You-Min Hu
- Institute of Medical Sciences and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiang-Yang Lu
- From the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China
| | - Michael X Zhu
- From the College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China.,Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Tian-Le Xu
- Discipline of Neuroscience, Department of Anatomy, Histology, and Embryology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, 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 Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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6
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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] [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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7
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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: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [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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8
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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] [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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9
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Abstract
Acid-sensing ion channels (ASICs) are proton-gated cation channels that are widely expressed in both the peripheral and central nervous systems. ASICs contribute to a variety of pathophysiological conditions that involve tissue acidosis, such as ischemic stroke, epileptic seizures and multiple sclerosis. Although much progress has been made in researching the structure-function relationship and pharmacology of ASICs, little is known about the trafficking of ASICs and its contribution to ASIC function. The recent identification of the mechanism of membrane insertion and endocytosis of ASIC1a highlights the emerging role of ASIC trafficking in regulating its pathophysiological functions. In this review, we summarize the recent advances and discuss future directions on this topic.
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Affiliation(s)
- Wei-Zheng Zeng
- a Discipline of Neuroscience and Department of Anatomy; Histology and Embryology; Institute of Medical Sciences ; Shanghai Jiao Tong University School of Medicine ; Shanghai 200025 , P.R. China
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10
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Osmakov DI, Andreev YA, Kozlov SA. Acid-sensing ion channels and their modulators. BIOCHEMISTRY (MOSCOW) 2015; 79:1528-45. [PMID: 25749163 DOI: 10.1134/s0006297914130069] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
According to a modern look acid-sensing ion channels (ASICs) are one of the most important receptors that perceive pH change in the body. ASICs represent proton-gated Na+-selective channels, which are expressed in neurons of the central and peripheral nervous system. These channels are attracting attention of researchers around the world, as they are involved in various physiological processes in the body. Drop of pH may occur in tissues in norm (e.g. the accumulation of lactic acid, the release of protons upon ATP hydrolysis) and pathology (inflammation, ischemic stroke, tissue damage and seizure). These processes are accompanied by unpleasant pain sensations, which may be short-lived or can lead to chronic inflammatory diseases. Modulators of ASIC channels activity are potential candidates for new effective analgesic and neuroprotection drugs. This review summarizes available information about structure, function, and physiological role of ASIC channels. In addition a description of all known ligands of these channels and their practical relevance is provided.
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Affiliation(s)
- D I Osmakov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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11
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Kellenberger S, Schild L. International Union of Basic and Clinical Pharmacology. XCI. Structure, Function, and Pharmacology of Acid-Sensing Ion Channels and the Epithelial Na+ Channel. Pharmacol Rev 2014; 67:1-35. [DOI: 10.1124/pr.114.009225] [Citation(s) in RCA: 193] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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12
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Zhao WS, Wang J, Ma XJ, Yang Y, Liu Y, Huang LD, Fan YZ, Cheng XY, Chen HZ, Wang R, Yu Y. Relative motions between left flipper and dorsal fin domains favour P2X4 receptor activation. Nat Commun 2014; 5:4189. [PMID: 24943126 DOI: 10.1038/ncomms5189] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 05/22/2014] [Indexed: 01/09/2023] Open
Abstract
Channel gating in response to extracellular ATP is a fundamental process for the physiological functions of P2X receptors. Here we identify coordinated allosteric changes in the left flipper (LF) and dorsal fin (DF) domains that couple ATP-binding to channel gating. Engineered disulphide crosslinking or zinc bridges between the LF and DF domains that constrain their relative motions significantly influence channel gating of P2X4 receptors, confirming the essential role of these allosteric changes. ATP-binding-induced alterations in interdomain hydrophobic interactions among I208, L217, V291 and the aliphatic chain of K193 correlate well with these coordinated relative movements. Mutations on those four residues lead to impaired or fully abolished channel activations of P2X4 receptors. Our data reveal that ATP-binding-induced altered interdomain hydrophobic interactions and the concomitant coordinated motions of LF and DF domains are allosteric events essential for the channel gating of P2X4 receptors.
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Affiliation(s)
- Wen-Shan Zhao
- 1] Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [2] Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China [3]
| | - Jin Wang
- 1] Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [2]
| | - Xiao-Juan Ma
- 1] Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [2] Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China [3]
| | - Yang Yang
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yan Liu
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Li-Dong Huang
- Institute of Medical Sciences and Department of Pharmacology, 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 Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hong-Zhuan Chen
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Rui Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
| | - Ye Yu
- 1] Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [2] College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
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13
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Huang LD, Fan YZ, Tian Y, Yang Y, Liu Y, Wang J, Zhao WS, Zhou WC, Cheng XY, Cao P, Lu XY, Yu Y. Inherent dynamics of head domain correlates with ATP-recognition of P2X4 receptors: insights gained from molecular simulations. PLoS One 2014; 9:e97528. [PMID: 24878662 PMCID: PMC4039465 DOI: 10.1371/journal.pone.0097528] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 04/22/2014] [Indexed: 11/19/2022] Open
Abstract
P2X receptors are ATP-gated ion channels involved in many physiological functions, and determination of ATP-recognition (AR) of P2X receptors will promote the development of new therapeutic agents for pain, inflammation, bladder dysfunction and osteoporosis. Recent crystal structures of the zebrafish P2X4 (zfP2X4) receptor reveal a large ATP-binding pocket (ABP) located at the subunit interface of zfP2X4 receptors, which is occupied by a conspicuous cluster of basic residues to recognize triphosphate moiety of ATP. Using the engineered affinity labeling and molecular modeling, at least three sites (S1, S2 and S3) within ABP have been identified that are able to recognize the adenine ring of ATP, implying the existence of at least three distinct AR modes in ABP. The open crystal structure of zfP2X4 confirms one of three AR modes (named AR1), in which the adenine ring of ATP is buried into site S1 while the triphosphate moiety interacts with clustered basic residues. Why architecture of ABP favors AR1 not the other two AR modes still remains unexplored. Here, we examine the potential role of inherent dynamics of head domain, a domain involved in ABP formation, in AR determinant of P2X4 receptors. In silico docking and binding free energy calculation revealed comparable characters of three distinct AR modes. Inherent dynamics of head domain, especially the downward motion favors the preference of ABP for AR1 rather than AR2 and AR3. Along with the downward motion of head domain, the closing movement of loop139-146 and loop169-183, and structural rearrangements of K70, K72, R298 and R143 enabled ABP to discriminate AR1 from other AR modes. Our observations suggest the essential role of head domain dynamics in determining AR of P2X4 receptors, allowing evaluation of new strategies aimed at developing specific blockers/allosteric modulators by preventing the dynamics of head domain associated with both AR and channel activation of P2X4 receptors.
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Affiliation(s)
- Li-Dong Huang
- Department of Pharmacology and Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ying-Zhe Fan
- Putuo District Center Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai, China
| | - Yun Tian
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
| | - Yang Yang
- Department of Pharmacology and Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Liu
- Department of Pharmacology and Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jin Wang
- Department of Pharmacology and Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wen-Shan Zhao
- Department of Pharmacology and Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wen-Chao Zhou
- Department of Pharmacology and Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Putuo District Center Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai, China
| | - Xiao-Yang Cheng
- Department of Pharmacology and Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Peng Cao
- Jiangsu Province Institute of Traditional Chinese Medicine, Nanjing, Jiangsu, China
| | - Xiang-Yang Lu
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
| | - Ye Yu
- Department of Pharmacology and Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
- * E-mail:
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14
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Charbonneau DM, Beauregard M. Role of key salt bridges in thermostability of G. thermodenitrificans EstGtA2: distinctive patterns within the new bacterial lipolytic enzyme subfamily XIII.2 [corrected]. PLoS One 2013; 8:e76675. [PMID: 24116134 PMCID: PMC3792869 DOI: 10.1371/journal.pone.0076675] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 08/24/2013] [Indexed: 02/07/2023] Open
Abstract
Bacterial lipolytic enzymes were originally classified into eight different families defined by Arpigny and Jaeger (families I-VIII). Recently, the discovery of new lipolytic enzymes allowed for extending the original classification to fourteen families (I-XIV). We previously reported that G. thermodenitrificans EstGtA2 (access no. AEN92268) belonged to a novel group of bacterial lipolytic enzymes. Here we propose a 15(th) family (family XV) and suggest criteria for the assignation of protein sequences to the N' subfamily. Five selected salt bridges, hallmarks of the N' subfamily (E3/R54, E12/R37, E66/R140, D124/K178 and D205/R220) were disrupted in EstGtA2 using a combinatorial alanine-scanning approach. A set of 14 (R/K→A) mutants was produced, including five single, three double, three triple and three quadruple mutants. Despite a high tolerance to non-conservative mutations for folding, all the alanine substitutions were destabilizing (decreasing T m by 5 to 14°C). A particular combination of four substitutions exceeded this tolerance and prevents the correct folding of EstGtA2, leading to enzyme inactivation. Although other mutants remain active at low temperatures, the accumulation of more than two mutations had a dramatic impact on EstGtA2 activity at high temperatures suggesting an important role of these conserved salt bridge-forming residues in thermostability of lipolytic enzymes from the N' subfamily. We also identified a particular interloop salt bridge in EstGtA2 (D194/H222), located at position i -2 and i -4 residues from the catalytic Asp and His respectively which is conserved in other related bacterial lipolytic enzymes (families IV and XIII) with high tolerance to mutations and charge reversal. We investigated the role of residue identity at position 222 in controlling stability-pH dependence in EstGtA2. The introduction of a His to Arg mutation led to increase thermostability under alkaline pH. Our results suggest primary targets for optimization of EstGtA2 for specific biotechnological purposes.
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Affiliation(s)
- David M. Charbonneau
- Département de chimie-physique, Centre de recherche sur les matériaux lignocellulosiques, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
- PROTEO (Quebec network for research on protein structure, function and engineering), Université Laval, Québec, Québec, Canada
| | - Marc Beauregard
- Département de chimie-physique, Centre de recherche sur les matériaux lignocellulosiques, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
- PROTEO (Quebec network for research on protein structure, function and engineering), Université Laval, Québec, Québec, Canada
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15
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Histamine up-regulates astrocytic glutamate transporter 1 and protects neurons against ischemic injury. Neuropharmacology 2013; 77:156-66. [PMID: 23791559 DOI: 10.1016/j.neuropharm.2013.06.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 05/13/2013] [Accepted: 06/06/2013] [Indexed: 11/22/2022]
Abstract
Astrocytic glutamate transporter 1 (GLT-1) is responsible for the majority of extracellular glutamate clearance and is essential for preventing excitotoxicity in the brain. Up-regulation of GLT-1 shows benefit effect on ischemia-induced neuronal damage. In present study, we examined the effect of histamine, a neurotransmitter or neuromodulator, on GLT-1 expression and function. In acute hippocampal slices, histamine selectively increased GLT-1 expression independent of neuronal activities. Similar up-regulation of GLT-1 was also observed after histamine treatment in pure cultured astrocytes, which was abolished by H1 receptor antagonist or PKC inhibitor. Cell surface biotinylation and whole-cell patch recordings of glutamate transporter current confirmed the up-regulation of functional GLT-1 following histamine exposure. Histamine treatment decreased the extracellular glutamate content and alleviated neuronal cell death induced by exogenous glutamate challenge. Moreover, we found a significant neuroprotective effect of histamine in brain slices after oxygen-glucose deprivation (OGD). In addition, histidine, the precursor of histamine, also showed neuroprotection against ischemic injury, which was accompanied by reversion of declined expression of GLT-1 in adult rats subjected to middle cerebral artery occlusion (MCAO). These neuroprotective effects of histamine/histidine were blocked by GLT-1 specific inhibitor dihydrokainate or H1 receptor antagonist. In summary, our results suggest that histamine up-regulates GLT-1 expression and function via astrocytic H1 receptors, thus resulting in neuroprotection against excitotoxicity and ischemic injury.
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16
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Molecular mechanism of constitutive endocytosis of Acid-sensing ion channel 1a and its protective function in acidosis-induced neuronal death. J Neurosci 2013; 33:7066-78. [PMID: 23595764 DOI: 10.1523/jneurosci.5206-12.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are proton-gated cation channels widely expressed in the peripheral and CNSs, which critically contribute to a variety of pathophysiological conditions that involve tissue acidosis, such as ischemic stroke and epileptic seizures. However, the trafficking mechanisms of ASICs and the related proteins remain largely unknown. Here, we demonstrate that ASIC1a, the main ASIC subunit in the brain, undergoes constitutive endocytosis in a clathrin- and dynamin-dependent manner in both mouse cortical neurons and heterologous cell cultures. The endocytosis of ASIC1a was inhibited by either the small molecular inhibitor tyrphostin A23 or knockdown of the core subunit of adaptor protein 2 (AP2) μ2 using RNA interference, supporting a clathrin-dependent endocytosis of ASIC1a. In addition, the internalization of ASIC1a was blocked by dominant-negative dynamin1 mutation K44A and the small molecular inhibitor dynasore, suggesting that it is also dynamin-dependent. We show that the membrane-proximal residues (465)LCRRG(469) at the cytoplasmic C terminus of ASIC1a are critical for interaction with the endogenous adaptor protein complex and inhibition of ASIC1a internalization strongly exacerbated acidosis-induced death of cortical neurons from wild-type but not ASIC1a knock-out mice. Together, these results reveal the molecular mechanism of ASIC1a internalization and suggest the importance of endocytic pathway in functional regulation of ASIC1a channels as well as neuronal damages mediated by these channels during neurodegeneration.
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17
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Sherwood TW, Frey EN, Askwith CC. Structure and activity of the acid-sensing ion channels. Am J Physiol Cell Physiol 2012; 303:C699-710. [PMID: 22843794 DOI: 10.1152/ajpcell.00188.2012] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The acid-sensing ion channels (ASICs) are a family of proton-sensing channels expressed throughout the nervous system. Their activity is linked to a variety of complex behaviors including fear, anxiety, pain, depression, learning, and memory. ASICs have also been implicated in neuronal degeneration accompanying ischemia and multiple sclerosis. As a whole, ASICs represent novel therapeutic targets for several clinically important disorders. An understanding of the correlation between ASIC structure and function will help to elucidate their mechanism of action and identify potential therapeutics that specifically target these ion channels. Despite the seemingly simple nature of proton binding, multiple studies have shown that proton-dependent gating of ASICs is quite complex, leading to activation and desensitization through distinct structural components. This review will focus on the structural aspects of ASIC gating in response to both protons and the newly discovered activators GMQ and MitTx. ASIC modulatory compounds and their action on proton-dependent gating will also be discussed. This review is dedicated to the memory of Dale Benos, who made a substantial contribution to our understanding of ASIC activity.
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Affiliation(s)
- Thomas W Sherwood
- Dept. of Neuroscience, The Ohio State Univ. Wexner Medical Center, Columbus, OH 43210, USA
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