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Chen Q, Zhu X, Kang G, Yu Q, Liu Q, Du L, Yang Y, He X, Zhao Y, Zhang J, Hu Y, Ren B. Identification and functional characterization of female antennae-biased odorant receptor 23 involved in acetophenone detection of the Indian meal moth Plodia interpunctella. Insect Sci 2024; 31:59-78. [PMID: 37464967 DOI: 10.1111/1744-7917.13220] [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] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 04/23/2023] [Accepted: 04/25/2023] [Indexed: 07/20/2023]
Abstract
The Indian meal moth, Plodia interpunctella (Lepidoptera: Pyralidae), a globally distributed storage pest, relies on odors that are emitted from stored foods to select a suitable substrate for oviposition. However, the molecular mechanism underlying the chemical communication between P. interpunctella and its host remains elusive. In this study, 130 chemosensory genes were identified from the transcriptomes of 7 P. interpunctella tissues, and the quantitative expression levels of all 56 P. interpunctella odorant receptor genes (PintORs) were validated using real-time quantitative polymerase chain reaction. The functional characteristics of 5 PintORs with female antennae-biased expression were investigated using 2-electrode voltage clamp recordings in Xenopus laevis oocytes. PintOR23 was found to be specifically tuned to acetophenone. Acetophenone could elicit a significant electrophysiological response and only attracted mated females when compared with males and virgin females. In addition, molecular docking predicted that the hydrogen bonding sites, TRP-335 and ALA-167, might play key roles in the binding of PintOR23 to acetophenone. Our study provides valuable insights into the olfactory mechanism of oviposition substrate detection and localization in P. interpunctella and points toward the possibility of developing eco-friendly odorant agents to control pests of stored products.
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Affiliation(s)
- Qi Chen
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
| | - Xiaoyan Zhu
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
| | - Guoqing Kang
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
| | - Qiling Yu
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
| | - Qingxin Liu
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
| | - Lin Du
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
| | - Yi Yang
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
| | - Xinyu He
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
| | - Ying Zhao
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
| | - Junjie Zhang
- Engineering Research Center of Natural Enemies, Institute of Biological Control, Jilin Agricultural University, Changchun, China
| | - Ying Hu
- Engineering Research Center of Natural Enemies, Institute of Biological Control, Jilin Agricultural University, Changchun, China
| | - Bingzhong Ren
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, School of Life Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, China
- Jilin Provincial Engineering Laboratory of Avian Ecology and Conservation Genetics, Northeast Normal University, Changchun, China
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Xu XY, Zhang FF, Gan J, Zhang MY, Shen ZS, Guo Q, Teng Y, Ji JW, Cao JL, Tang QY, Zhang Z. Identification of the Acid-Sensitive Site Critical for Chloral Hydrate (CH) Activation of the Proton-Activated Chloride Channel. J Neurosci 2023; 43:526-39. [PMID: 36283831 DOI: 10.1523/JNEUROSCI.0482-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 09/22/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022] Open
Abstract
The transmembrane protein TMEM206 was recently identified as the molecular basis of the extracellular proton-activated Cl- channel (PAC), which plays an essential role in neuronal death in ischemia-reperfusion. The PAC channel is activated by extracellular acid, but the proton-sensitive mechanism remains unclear, although different acid-sensitive pockets have been suggested based on the cryo-EM structure of the human PAC (hPAC) channel. In the present study, we firstly identified two acidic amino acid residues that removed the pH-dependent activation of the hPAC channel by neutralization all the conservative negative charged residues located in the extracellular domain of the hPAC channel and some positively charged residues at the hotspot combined with two-electrode voltage-clamp (TEVC) recording in the Xenopus oocytes system. Double-mutant cycle analysis and double cysteine mutant of these two residues proved that these two residues cooperatively form a proton-sensitive site. In addition, we found that chloral hydrate activates the hPAC channel depending on the normal pH sensitivity of the hPAC channel. Furthermore, the PAC channel knock-out (KO) male mice (C57BL/6J) resist chloral hydrate-induced sedation and hypnosis. Our study provides a molecular basis for understanding the proton-dependent activation mechanism of the hPAC channel and a novel drug target of chloral hydrate.SIGNIFICANCE STATEMENT Proton-activated Cl- channel (PAC) channels are widely distributed in the nervous system and play a vital pathophysiological role in ischemia and endosomal acidification. The main discovery of this paper is that we identified the proton activation mechanism of the human proton-activated chloride channel (hPAC). Intriguingly, we also found that anesthetic chloral hydrate can activate the hPAC channel in a pH-dependent manner. We found that the chloral hydrate activates the hPAC channel and needs the integrity of the pH-sensitive site. In addition, the PAC channel knock-out (KO) mice are resistant to chloral hydrate-induced anesthesia. The study on PAC channels' pH activation mechanism enables us to better understand PAC's biophysical mechanism and provides a novel target of chloral hydrate.
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Lee S, Seol HS, Eom S, Lee J, Kim C, Park JH, Kim TH, Lee JH. Hydroxy Pentacyclic Triterpene Acid, Kaempferol, Inhibits the Human 5-Hydroxytryptamine Type 3A Receptor Activity. Int J Mol Sci 2022; 23:544. [PMID: 35008969 DOI: 10.3390/ijms23010544] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/03/2022] [Accepted: 01/03/2022] [Indexed: 12/31/2022] Open
Abstract
Monoamine serotonin is a major neurotransmitter that acts on a wide range of central nervous system and peripheral nervous system functions and is known to have a role in various processes. Recently, it has been found that 5-HT is involved in cognitive and memory functions through interaction with cholinergic pathways. The natural flavonoid kaempferol (KAE) extracted from Cudrania tricuspidata is a secondary metabolite of the plant. Recently studies have confirmed that KAE possesses a neuroprotective effect because of its strong antioxidant activity. It has been confirmed that KAE is involved in the serotonergic pathway through an in vivo test. However, these results need to be confirmed at the molecular level, because the exact mechanism that is involved in such effects of KAE has not yet been elucidated. Therefore, the objective of this study is to confirm the interaction of KAE with 5-HT3A through electrophysiological studies at the molecular level using KAE extracted from Cudrania tricuspidata. This study confirmed the interaction between 5-HT3A and KAE at the molecular level. KAE inhibited 5-HT3A receptors in a concentration-dependent and voltage-independent manner. Site-directed mutagenesis and molecular-docking studies confirmed that the binding sites D177 and F199 are the major binding sites of human 5-HT3A receptors of KAE.
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Imran S, Tsuchiya Y, Tran STH, Katsuhara M. Identification and Characterization of Rice OsHKT1;3 Variants. Plants (Basel) 2021; 10:plants10102006. [PMID: 34685816 PMCID: PMC8537747 DOI: 10.3390/plants10102006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 05/23/2023]
Abstract
In rice, the high-affinity K+ transporter, OsHKT1;3, functions as a Na+-selective transporter. mRNA variants of OsHKT1;3 have been reported previously, but their functions remain unknown. In this study, five OsHKT1;3 variants (V1-V5) were identified from japonica rice (Nipponbare) in addition to OsHKT1;3_FL. Absolute quantification qPCR analyses revealed that the transcript level of OsHKT1;3_FL was significantly higher than other variants in both the roots and shoots. Expression levels of OsHKT1;3_FL, and some variants, increased after 24 h of salt stress. Two electrode voltage clamp experiments in a heterologous expression system using Xenopus laevis oocytes revealed that oocytes expressing OsHKT1;3_FL and all of its variants exhibited smaller Na+ currents. The presented data, together with previous data, provide insights to understanding how OsHKT family members are involved in the mechanisms of ion homeostasis and salt tolerance in rice.
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Affiliation(s)
- Shahin Imran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan or (S.I.); (Y.T.); (S.T.H.T.)
- Department of Agronomy, Khulna Agricultural University, Khulna 9100, Bangladesh
| | - Yoshiyuki Tsuchiya
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan or (S.I.); (Y.T.); (S.T.H.T.)
| | - Sen Thi Huong Tran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan or (S.I.); (Y.T.); (S.T.H.T.)
- Faculty of Agronomy, University of Agriculture and Forestry, Hue University, Hue 530000, Vietnam
| | - Maki Katsuhara
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan or (S.I.); (Y.T.); (S.T.H.T.)
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Eom S, Lee J, Baek YB, Yeom HD, Lee S, Kim C, Park Y, Park SI, Lee CM, Lee JH. Identification and molecular study on the interaction of Schisandrin C with human 5-HT 3A receptor. Eur J Pharmacol 2021; 906:174220. [PMID: 34081905 DOI: 10.1016/j.ejphar.2021.174220] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 01/01/2023]
Abstract
Schisandrin C (Sch C) is one of the main components of Schisandra chinensis (Schisandra). Since the olden times, Schisandra has been used as a traditional herbal medicine in Asia. Recent studies have shown that Schisandra is effective against irritable bowel syndrome (IBS) in an animal model and affects IBS through the 5-HT3A pathway in the IBS rat model. However, there lacks fundamental research on the interaction of specific components of Schisandra with the 5-HT3A receptor for the treatment of IBS. We hypothesized that a component of Schisandra binds to the 5-HT3A receptor and identified Sch C via a screening work using two electrode-voltage clamps (TEVC). Thus, we aimed to elucidate the neuropharmacological actions between Sch C and the 5-HT3A receptor at molecular and cellular levels. Co-treatment of Sch C with 5-HT inhibited I5-HT in a reversible, concentrate-dependent, like-competition, and voltage-independent manner, and IC50 values of Sch C. Besides, the main binding positions of Sch C were identified through 3D modeling and point mutation were V225A and V288Y on 5-HT3A receptor. Thus, we suggest the potential of Sch C in treating IBS in a manner that suppresses excessive neuronal serotonin signaling in the synapse of sensory neurons and enterochromaffin (EC) cells. In conclusion, the results demonstrate the mechanism of interaction between Sch C and 5-HT3A receptor and reveal Sch C as a novel antagonist.
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Affiliation(s)
- Sanung Eom
- Department of Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Jaeeun Lee
- Department of Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Yeong-Bin Baek
- Department of Veterinary Medicine, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, South Korea
| | | | - Shinhui Lee
- Department of Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Chaelin Kim
- Department of Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Youngseo Park
- Department of Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Sang-Ik Park
- Department of Veterinary Medicine, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, South Korea
| | - Chang-Min Lee
- Department of Veterinary Medicine, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, South Korea.
| | - Junho H Lee
- Department of Biotechnology, Chonnam National University, Gwangju, South Korea.
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Lee S, Jung W, Eom S, Yeom HD, Park HD, Lee JH. Molecular Regulation of Betulinic Acid on α3β4 Nicotinic Acetylcholine Receptors. Molecules 2021; 26:2659. [PMID: 34062829 PMCID: PMC8125762 DOI: 10.3390/molecules26092659] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/17/2021] [Accepted: 04/26/2021] [Indexed: 11/24/2022] Open
Abstract
Betulinic acid (BA) is a major constituent of Zizyphus seeds that have been long used as therapeutic agents for sleep-related issues in Asia. BA is a pentacyclic triterpenoid. It also possesses various anti-cancer and anti-inflammatory effects. Current commercially available sleep aids typically use GABAergic regulation, for which many studies are being actively conducted. However, few studies have focused on acetylcholine receptors that regulate wakefulness. In this study, we utilized BA as an antagonist of α3β4 nicotinic acetylcholine receptors (α3β4 nAChRs) known to regulate rapid-eye-movement (REM) sleep and wakefulness. Effects of BA on α3β4 nAChRs were concentration-dependent, reversible, voltage-independent, and non-competitive. Site-directed mutagenesis and molecular-docking studies confirmed the binding of BA at the molecular level and showed that the α3 subunit L257 and the β4 subunit I263 residues affected BA binding. These data demonstrate that BA can bind to a binding site different from the site for the receptor's ligand, acetylcholine (ACh). This suggests that BA may be an effective antagonist that is unaffected by large amounts of ACh released during wakefulness and REM sleep. Based on the above experimental results, BA is likely to be a therapeutically useful sleep aid and sedative.
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Affiliation(s)
- Shinhui Lee
- Department of Biotechnology, Chonnam National University, Gwangju 61186, Korea; (S.L.); (S.E.)
| | - Woog Jung
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea;
| | - Sanung Eom
- Department of Biotechnology, Chonnam National University, Gwangju 61186, Korea; (S.L.); (S.E.)
| | | | - Heui-Dong Park
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea;
| | - Junho H. Lee
- Department of Biotechnology, Chonnam National University, Gwangju 61186, Korea; (S.L.); (S.E.)
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Abstract
In this method paper, we describe protocols for using membrane-tethered peptide toxins (T-toxins) to study the structure/function and biophysics of toxin-channel interactions with two-electrode voltage clamp (TEVC). Here, we show how T-toxins can be used to determine toxin equilibrium affinity, to quantify toxin surface level by enzyme-linked immunosorbent assay (ELISA) and/or single-molecule total internal reflection fluorescence (smTIRF) microscopy, to assess toxin association and dissociations rate, to identify toxin residues critical to binding via scanning mutagenesis, and to study of toxin blocking mechanism. The sea anemone type I (SAK1) toxin HmK and a potassium channel are used to demonstrate the strategies. T-toxins offer experimental flexibility that facilitates studies of toxin variants by mutation of the expression plasmid, avoiding the need to synthesize and purify individual peptides, speeding and reducing the cost of studies. T-toxins can be applied to peptide toxins that target pores or regulatory domains, that inhibit or activate, that are derived from different species, and that bind to different types of ion channels.
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Affiliation(s)
- Ruiming Zhao
- Departments of Pediatrics, Physiology & Biophysics, and Pharmaceutical Sciences, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, CA, United States
| | - Steve A N Goldstein
- Departments of Pediatrics, Physiology & Biophysics, and Pharmaceutical Sciences, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, CA, United States.
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Temme L, Bechthold E, Schreiber JA, Gawaskar S, Schepmann D, Robaa D, Sippl W, Seebohm G, Wünsch B. Negative allosteric modulators of the GluN2B NMDA receptor with phenylethylamine structure embedded in ring-expanded and ring-contracted scaffolds. Eur J Med Chem 2020; 190:112138. [PMID: 32070917 DOI: 10.1016/j.ejmech.2020.112138] [Citation(s) in RCA: 4] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 01/20/2020] [Accepted: 02/09/2020] [Indexed: 11/26/2022]
Abstract
A set of GluN2B NMDA receptor antagonists with conformationally restricted phenylethylamine substructure was prepared and pharmacologically evaluated. The phenylethylamine substructure was embedded in ring expanded 3-benzazocines 4 as well as ring-contracted tetralinamines 6 and indanamines 7. The ligands 4, 6 and 7 were synthesized by reductive alkylation of secondary amine 11, reductive amination of ketones 12 and 16 and nucleophilic substitution of nosylates 14 and 17. The moderate GluN2B affinity of 3-benzazocine 4d (Ki = 32 nM) translated into moderate cytoprotective activity (IC50 = 890 nM) and moderate ion channel inhibition (60% at 10 μM) in two-electrode voltage clamp experiments with GluN1a/GluN2B expressing oocytes. Although some of the tetralinamines 6 and indanamines 7 showed very high GluN2B affinity (e.g. Ki (7f) = 3.2 nM), they could not inhibit glutamate/glycine inducted cytotoxicity. The low cytoprotective activity of 3-benzazocines 4, tetralinamines 6 and indanamines 7 was attributed to the missing OH moiety at the benzene ring and/or in benzylic position. Docking studies showed that the novel GluN2B ligands adopt similar binding poses as Ro 25-6981 with the central H-bond interaction between the protonated amino moiety of the ligands and the carbamoyl moiety of Gln110. However, due to the lack of a second H-bond forming group, the ligands can adopt two binding poses within the ifenprodil binding pocket.
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Affiliation(s)
- Louisa Temme
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Corrensstraße 48, D-48149, Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), Westfälische Wilhelms-Universität, Münster, Germany
| | - Elena Bechthold
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
| | - Julian A Schreiber
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Corrensstraße 48, D-48149, Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), Westfälische Wilhelms-Universität, Münster, Germany; Institut für Pharmazie der Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Straße 4, 06120, Halle (Saale), Germany
| | - Sandeep Gawaskar
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Corrensstraße 48, D-48149, Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), Westfälische Wilhelms-Universität, Münster, Germany
| | - Dirk Schepmann
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
| | - Dina Robaa
- Cellular Electrophysiology and Molecular Biology, Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, D-48149, Münster, Germany
| | - Wolfgang Sippl
- Cellular Electrophysiology and Molecular Biology, Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, D-48149, Münster, Germany
| | - Guiscard Seebohm
- Institut für Pharmazie der Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Straße 4, 06120, Halle (Saale), Germany
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Corrensstraße 48, D-48149, Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), Westfälische Wilhelms-Universität, Münster, Germany.
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Ning J, Ren J, Xiong Y, Wu Y, Zhangsun M, Zhangsun D, Zhu X, Luo S. Identification of Crucial Residues in α-Conotoxin EI Inhibiting Muscle Nicotinic Acetylcholine Receptor. Toxins (Basel) 2019; 11:toxins11100603. [PMID: 31623211 PMCID: PMC6832962 DOI: 10.3390/toxins11100603] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 09/30/2019] [Accepted: 10/08/2019] [Indexed: 12/31/2022] Open
Abstract
α-Conotoxins (α-CTxs) are small disulfide-rich peptides from venom of Conus species that target nicotinic acetylcholine receptors (nAChRs). The muscle-type nAChRs have been recognized as a potential target for several diseases, such as myogenic disorders, muscle dystrophies, and myasthenia gravis. EI, an α4/7-CTx, mainly blocks α1β1δε nAChRs and has an extra N-terminal extension of three amino acids. In this study, the alanine scanning (Ala-scan) mutagenesis was applied in order to identify key residues of EI for binding with mouse α1β1δε nAChR. The Ala-substituted analogues were tested for their abilities of modulating muscle and neuronal nAChRs in Xenopus laevis oocytes using two-electrode voltage clamp (TEVC) recordings. Electrophysiological results indicated that the vital residues for functional activity of EI were His-7, Pro-8, Met-12, and Pro-15. These changes exhibited a significant decrease in potency of EI against mouse α1β1δε nAChR. Interestingly, replacing the critical serine (Ser) at position 13 with an alanine (Ala) residue resulted in a 2-fold increase in potency at the α1β1δε nAChR, and showed loss of activity on α3β2 and α3β4 nAChRs. Selectivity and potency of [S13A] EI was improved compared with wild-type EI (WT EI). In addition, the structure–activity relationship (SAR) of EI revealed that the “Arg1–Asn2–Hyp3” residues at the N-terminus conferred potency at the muscle-type nAChRs, and the deletion analogue △1–3 EI caused a total loss of activity at the α1β1δε nAChR. Circular dichroism (CD) spectroscopy studies demonstrated that activity loss of truncated analogue △1–3 EI for α1β1δε nAChR is attributed to disturbance of the secondary structure. In this report, an Ala-scan mutagenesis strategy is presented to identify crucial residues that are significantly affecting potency of E1 for mouse α1β1δε nAChR. It may also be important in remodeling of some novel ligands for inhibiting muscle-type nAChRs.
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Affiliation(s)
- Jiong Ning
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.
| | - Jie Ren
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.
| | - Yang Xiong
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.
| | - Yong Wu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.
| | - Manqi Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.
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George AA, Bloy A, Miwa JM, Lindstrom JM, Lukas RJ, Whiteaker P. Isoform-specific mechanisms of α3β4*-nicotinic acetylcholine receptor modulation by the prototoxin lynx1. FASEB J 2017; 31:1398-1420. [PMID: 28100642 DOI: 10.1096/fj.201600733r] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [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: 06/29/2016] [Accepted: 12/12/2016] [Indexed: 11/11/2022]
Abstract
This study investigates-for the first time to our knowledge-the existence and mechanisms of functional interactions between the endogenous mammalian prototoxin, lynx1, and α3- and β4-subunit-containing human nicotinic acetylcholine receptors (α3β4*-nAChRs). Concatenated gene constructs were used to express precisely defined α3β4*-nAChR isoforms (α3β4)2β4-, (α3β4)2α3-, (α3β4)2α5(398D)-, and (α3β4)2α5(398N)-nAChR in Xenopus oocytes. In the presence or absence of lynx1, α3β4*-nAChR agonist responses were recorded by using 2-electrode voltage clamp and single-channel electrophysiology, whereas radioimmunolabeling measured cell-surface expression. Lynx1 reduced (α3β4)2β4-nAChR function principally by lowering cell-surface expression, whereas single-channel effects were primarily responsible for reducing (α3β4)2α3-nAChR function [decreased unitary conductance (≥50%), altered burst proportions (3-fold reduction in the proportion of long bursts), and enhanced closed dwell times (3- to 6-fold increase)]. Alterations in both cell-surface expression and single-channel properties accounted for the reduction in (α3β4)2α5-nAChR function that was mediated by lynx1. No effects were observed when α3β4*-nAChRs were coexpressed with mutated lynx1 (control). Lynx1 is expressed in the habenulopeduncular tract, where α3β4*-α5*-nAChR subtypes are critical contributors to the balance between nicotine aversion and reward. This gives our findings a high likelihood of physiologic significance. The exquisite isoform selectivity of lynx1 interactions provides new insights into the mechanisms and allosteric sites [α(-)-interface containing] by which prototoxins can modulate nAChR function.-George, A. A., Bloy, A., Miwa, J. M., Lindstrom, J. M., Lukas, R. J., Whiteaker, P. Isoform-specific mechanisms of α3β4*-nicotinic acetylcholine receptor modulation by the prototoxin lynx1.
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Affiliation(s)
- Andrew A George
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA;
| | - Abigail Bloy
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.,Leeds Institute of Cancer and Pathology, St. James' University Hospital, Leeds, United Kingdom
| | - Julie M Miwa
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, USA
| | - Jon M Lindstrom
- Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania, USA
| | - Ronald J Lukas
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Paul Whiteaker
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
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11
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Gonnissen D, Qu Y, Langer K, Öztürk C, Zhao Y, Chen C, Seebohm G, Düfer M, Fuchs H, Galla HJ, Riehemann K. Comparison of cellular effects of starch-coated SPIONs and poly(lactic-co-glycolic acid) matrix nanoparticles on human monocytes. Int J Nanomedicine 2016; 11:5221-5236. [PMID: 27789942 PMCID: PMC5072557 DOI: 10.2147/ijn.s106540] [Citation(s) in RCA: 16] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Within the last years, progress has been made in the knowledge of the properties of medically used nanoparticles and their toxic effects, but still, little is known about their influence on cellular processes of immune cells. The aim of our comparative study was to present the influence of two different nanoparticle types on subcellular processes of primary monocytes and the leukemic monocyte cell line MM6. We used core-shell starch-coated superparamagnetic iron oxide nanoparticles (SPIONs) and matrix poly(lactic-co-glycolic acid) (PLGA) nanoparticles for our experiments. In addition to typical biocompatibility testing like the detection of necrosis or secretion of interleukins (ILs), we investigated the impact of these nanoparticles on the actin cytoskeleton and the two voltage-gated potassium channels Kv1.3 and Kv7.1. Induction of necrosis was not seen for PLGA nanoparticles and SPIONs in primary monocytes and MM6 cells. Likewise, no alteration in secretion of IL-1β and IL-10 was detected under the same experimental conditions. In contrast, IL-6 secretion was exclusively downregulated in primary monocytes after contact with both nanoparticles. Two-electrode voltage clamp experiments revealed that both nanoparticles reduce currents of the aforementioned potassium channels. The two nanoparticles differed significantly in their impact on the actin cytoskeleton, demonstrated via atomic force microscopy elasticity measurement and phalloidin staining. While SPIONs led to the disruption of the respective cytoskeleton, PLGA did not show any influence in both experimental setups. The difference in the effects on ion channels and the actin cytoskeleton suggests that nanoparticles affect these subcellular components via different pathways. Our data indicate that the alteration of the cytoskeleton and the effect on ion channels are new parameters that describe the influence of nanoparticles on cells. The results are highly relevant for medical application and further evaluation of nanomaterial biosafety.
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Affiliation(s)
- Dominik Gonnissen
- Center for Nanotechnology, Institute of Physics, University of Münster, Münster, Germany
| | - Ying Qu
- Center for Nanotechnology, Institute of Physics, University of Münster, Münster, Germany; National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Klaus Langer
- Institute of Pharmaceutical Technology and Biopharmacy, University of Münster, Münster
| | | | - Yuliang Zhao
- National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Chunying Chen
- National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Guiscard Seebohm
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases, University Hospital Münster
| | - Martina Düfer
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry
| | - Harald Fuchs
- Center for Nanotechnology, Institute of Physics, University of Münster, Münster, Germany
| | - Hans-Joachim Galla
- Department of Cell Biology/Biophysics, Institute of Biochemistry, University of Münster, Münster, Germany
| | - Kristina Riehemann
- Center for Nanotechnology, Institute of Physics, University of Münster, Münster, Germany
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12
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Margheritis E, Imperiali FG, Cinquetti R, Vollero A, Terova G, Rimoldi S, Girardello R, Bossi E. Amino acid transporter B(0)AT1 (slc6a19) and ancillary protein: impact on function. Pflugers Arch 2016; 468:1363-74. [PMID: 27255547 DOI: 10.1007/s00424-016-1842-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [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: 03/07/2016] [Revised: 05/04/2016] [Accepted: 05/29/2016] [Indexed: 12/16/2022]
Abstract
Amino acids play an important role in the metabolism of all organisms. Their epithelial re-absorption is due to specific transport proteins, such as B(0)AT1, a Na(+)-coupled neutral amino acid symporter belonging to the solute carrier 6 family. Here, a recently cloned fish orthologue, from the intestine of Salmo salar, was electrophysiologically characterized with the two-electrode voltage clamp technique, in Xenopus laevis oocytes heterologously expressing the transporter. Substrate specificity, apparent affinities and the ionic dependence of the transport mechanism were determined in the presence of specific collectrin. Results demonstrated that like the human, but differently from sea bass (Dicentrarchus labrax) orthologue, salmon B(0)AT1 needs to be associated with partner proteins to be correctly expressed at the oocyte plasma membrane. Cloning of sea bass collectrin and comparison of membrane expression and functionality of the B(0)AT1 orthologue transporters allowed a deeper investigation on the role of their interactions. The parameters acquired by electrophysiological and immunolocalization experiments in the mammalian and fish transporters contributed to highlight the dynamic of relations and impacts on transport function of the ancillary proteins. The comparative characterization of the physiological parameters of amino acid transporters with auxiliary proteins can help the comprehension of the regulatory mechanism of essential nutrient absorption.
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Affiliation(s)
- Eleonora Margheritis
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Francesca Guia Imperiali
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Raffaella Cinquetti
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Alessandra Vollero
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Genciana Terova
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
- Interuniversity Center "The Protein Factory", Politecnico di Milano, ICRM-CNR Milano and Università dell'Insubria, Via Mancinelli 7, I-20131, Milan, Italy
| | - Simona Rimoldi
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Rossana Girardello
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Elena Bossi
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy.
- Interuniversity Center "The Protein Factory", Politecnico di Milano, ICRM-CNR Milano and Università dell'Insubria, Via Mancinelli 7, I-20131, Milan, Italy.
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13
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Li B, Qiu J, Jayakannan M, Xu B, Li Y, Mayo GM, Tester M, Gilliham M, Roy SJ. AtNPF2.5 Modulates Chloride (Cl -) Efflux from Roots of Arabidopsis thaliana. Front Plant Sci 2016; 7:2013. [PMID: 28111585 PMCID: PMC5216686 DOI: 10.3389/fpls.2016.02013] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 12/19/2016] [Indexed: 05/18/2023]
Abstract
The accumulation of high concentrations of chloride (Cl-) in leaves can adversely affect plant growth. When comparing different varieties of the same Cl- sensitive plant species those that exclude relatively more Cl- from their shoots tend to perform better under saline conditions; however, the molecular mechanisms involved in maintaining low shoot Cl- remain largely undefined. Recently, it was shown that the NRT1/PTR Family 2.4 protein (NPF2.4) loads Cl- into the root xylem, which affects the accumulation of Cl- in Arabidopsis shoots. Here we characterize NPF2.5, which is the closest homolog to NPF2.4 sharing 83.2% identity at the amino acid level. NPF2.5 is predominantly expressed in root cortical cells and its transcription is induced by salt. Functional characterisation of NPF2.5 via its heterologous expression in yeast (Saccharomyces cerevisiae) and Xenopus laevis oocytes indicated that NPF2.5 is likely to encode a Cl- permeable transporter. Arabidopsis npf2.5 T-DNA knockout mutant plants exhibited a significantly lower Cl- efflux from roots, and a greater Cl- accumulation in shoots compared to salt-treated Col-0 wild-type plants. At the same time, [Formula: see text] content in the shoot remained unaffected. Accumulation of Cl- in the shoot increased following (1) amiRNA-induced knockdown of NPF2.5 transcript abundance in the root, and (2) constitutive over-expression of NPF2.5. We suggest that both these findings are consistent with a role for NPF2.5 in modulating Cl- transport. Based on these results, we propose that NPF2.5 functions as a pathway for Cl- efflux from the root, contributing to exclusion of Cl- from the shoot of Arabidopsis.
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Affiliation(s)
- Bo Li
- Australian Centre for Plant Functional GenomicsAdelaide, SA, Australia
- School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and TechnologyThuwal, Saudi Arabia
| | - Jiaen Qiu
- School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia
- ARC Centre of Excellence in Plant Energy BiologyAdelaide, SA, Australia
| | - Maheswari Jayakannan
- School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia
- ARC Centre of Excellence in Plant Energy BiologyAdelaide, SA, Australia
| | - Bo Xu
- School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia
- ARC Centre of Excellence in Plant Energy BiologyAdelaide, SA, Australia
| | - Yuan Li
- Australian Centre for Plant Functional GenomicsAdelaide, SA, Australia
- School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia
| | - Gwenda M. Mayo
- School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia
| | - Mark Tester
- Australian Centre for Plant Functional GenomicsAdelaide, SA, Australia
- School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and TechnologyThuwal, Saudi Arabia
| | - Matthew Gilliham
- School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia
- ARC Centre of Excellence in Plant Energy BiologyAdelaide, SA, Australia
- *Correspondence: Matthew Gilliham
| | - Stuart J. Roy
- Australian Centre for Plant Functional GenomicsAdelaide, SA, Australia
- School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia
- Stuart J. Roy
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14
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Hilbers F, Poulsen H. Electrophysiological Characterization of Na,K-ATPases Expressed in Xenopus laevis Oocytes Using Two-Electrode Voltage Clamping. Methods Mol Biol 2016; 1377:305-18. [PMID: 26695042 DOI: 10.1007/978-1-4939-3179-8_27] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
The transport of three Na(+) per two K(+) means that the Na,K-ATPase is electrogenic, and though the currents generated by the ion pump are small compared to ion channel currents, they can be measured using electrophysiology, both steady-state pumping and individual steps in the transport cycle. Various electrophysiological techniques have been used to study the endogenous pumps of the squid giant axon and of cardiac myocytes from for example rabbits. Here, we describe the characterization of heterologously expressed Na,K-ATPases using two-electrode voltage clamping (TEVC) and oocytes from the Xenopus laevis frog as the model cell. With this system, the effects of particular mutations can be studied, including the numerous mutations that in later years have been found to cause human diseases.
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15
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Tang QY, Larry T, Hendra K, Yamamoto E, Bell J, Cui M, Logothetis DE, Boland LM. Mutations in Nature Conferred a High Affinity Phosphatidylinositol 4,5-Bisphosphate-binding Site in Vertebrate Inwardly Rectifying Potassium Channels. J Biol Chem 2015; 290:16517-29. [PMID: 25957411 DOI: 10.1074/jbc.m115.640409] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [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: 01/28/2015] [Indexed: 11/06/2022] Open
Abstract
All vertebrate inwardly rectifying potassium (Kir) channels are activated by phosphatidylinositol 4,5-bisphosphate (PIP2) (Logothetis, D. E., Petrou, V. I., Zhang, M., Mahajan, R., Meng, X. Y., Adney, S. K., Cui, M., and Baki, L. (2015) Annu. Rev. Physiol. 77, 81-104; Fürst, O., Mondou, B., and D'Avanzo, N. (2014) Front. Physiol. 4, 404-404). Structural components of a PIP2-binding site are conserved in vertebrate Kir channels but not in distantly related animals such as sponges and sea anemones. To expand our understanding of the structure-function relationships of PIP2 regulation of Kir channels, we studied AqKir, which was cloned from the marine sponge Amphimedon queenslandica, an animal that represents the phylogenetically oldest metazoans. A requirement for PIP2 in the maintenance of AqKir activity was examined in intact oocytes by activation of a co-expressed voltage-sensing phosphatase, application of wortmannin (at micromolar concentrations), and activation of a co-expressed muscarinic acetylcholine receptor. All three mechanisms to reduce the availability of PIP2 resulted in inhibition of AqKir current. However, time-dependent rundown of AqKir currents in inside-out patches could not be re-activated by direct application to the inside membrane surface of water-soluble dioctanoyl PIP2, and the current was incompletely re-activated by the more hydrophobic arachidonyl stearyl PIP2. When we introduced mutations to AqKir to restore two positive charges within the vertebrate PIP2-binding site, both forms of PIP2 strongly re-activated the mutant sponge channels in inside-out patches. Molecular dynamics simulations validate the additional hydrogen bonding potential of the sponge channel mutants. Thus, nature's mutations conferred a high affinity activation of vertebrate Kir channels by PIP2, and this is a more recent evolutionary development than the structures that explain ion channel selectivity and inward rectification.
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Affiliation(s)
- Qiong-Yao Tang
- From the Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298, the Jiangsu Province Key Laboratory of Anesthesiology and Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, XuZhou Medical College, Xuzhou, 221004 Jiangsu Province, China
| | - Trevor Larry
- the Department of Biology, University of Richmond, Richmond, Virginia 23173
| | - Kalen Hendra
- the Department of Biology, University of Richmond, Richmond, Virginia 23173
| | - Erica Yamamoto
- the Department of Biology, University of Richmond, Richmond, Virginia 23173
| | - Jessica Bell
- the Department of Chemistry and Biochemistry, University of San Diego, San Diego, California 92110, and
| | - Meng Cui
- From the Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298
| | - Diomedes E Logothetis
- From the Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298
| | - Linda M Boland
- the Department of Biology, University of Richmond, Richmond, Virginia 23173
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16
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Moreau CJ, Niescierowicz K, Caro LN, Revilloud J, Vivaudou M. Ion channel reporter for monitoring the activity of engineered GPCRs. Methods Enzymol 2015; 556:425-54. [PMID: 25857794 DOI: 10.1016/bs.mie.2014.12.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ion channel-coupled receptor (ICCR) is a recent technology based on the fusion of G protein-coupled receptors (GPCRs) to an ion channel. Binding of ligands on the GPCR triggers conformational changes of the receptor that are mechanically transmitted to the ion channel gates, generating an electrical signal easily detectable with conventional electrophysiological techniques. ICCRs are heterologously expressed in Xenopus oocytes and offers several advantages such as: (i) real-time recordings on single cells, (ii) standard laboratory environment and inexpensive media for Xenopus oocytes maintenance, (iii) absence of protein purification steps, (iv) sensitivity to agonists and antagonists in concentration-dependent manner, (v) compatibility with a Gi/o protein activation assay based on Kir3.x channels, and (vi) ability to detect receptor activation independently of intracellular effectors. This last characteristic of ICCRs led to the development of a functional assay for G protein-"uncoupled" receptors such as GPCRs optimized for crystallization by alteration of their third intracellular (i3) loop. One of the most widely used approaches consists in replacing the i3 loop with the T4 phage lysozyme (T4L) domain that obstructs the access of G proteins to their binding site. We recently demonstrated that the ICCR technology can functionally characterize GPCRs(T4L). Two-electrode voltage-clamp (TEVC) recordings revealed that apparent affinities and sensitivities to ligands are not affected by T4L insertion, while ICCRs(T4L) displayed a partial agonist phenotype upon binding of full agonists, suggesting that ICCRs could detect intermediate-active states. This chapter aims to provide exhaustive details from molecular biology steps to electrophysiological recordings for the design and the characterization of ICCRs and ICCRs(T4L).
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17
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Ozoe Y, Kita T, Ozoe F, Nakao T, Sato K, Hirase K. Insecticidal 3-benzamido-N-phenylbenzamides specifically bind with high affinity to a novel allosteric site in housefly GABA receptors. Pestic Biochem Physiol 2013; 107:285-292. [PMID: 24267689 DOI: 10.1016/j.pestbp.2013.09.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/10/2013] [Accepted: 09/17/2013] [Indexed: 06/02/2023]
Abstract
γ-Aminobutyric acid (GABA) receptors (GABARs) are an important target for existing insecticides such as fiproles. These insecticides act as noncompetitive antagonists (channel blockers) for insect GABARs by binding to a site within the intrinsic channel of the GABAR. Recently, a novel class of insecticides, 3-benzamido-N-phenylbenzamides (BPBs), was shown to inhibit GABARs by binding to a site distinct from the site for fiproles. We examined the binding site of BPBs in the adult housefly by means of radioligand-binding and electrophysiological experiments. 3-Benzamido-N-(2,6-dimethyl-4-perfluoroisopropylphenyl)-2-fluorobenzamide (BPB 1) (the N-demethyl BPB) was a partial, but potent, inhibitor of [(3)H]4'-ethynyl-4-n-propylbicycloorthobenzoate (GABA channel blocker) binding to housefly head membranes, whereas the 3-(N-methyl)benzamido congener (the N-methyl BPB) had low or little activity. A total of 15 BPB analogs were tested for their abilities to inhibit [(3)H]BPB 1 binding to the head membranes. The N-demethyl analogs, known to be highly effective insecticides, potently inhibited the [(3)H]BPB 1 binding, but the N-methyl analogs did not even though they, too, are considered highly effective. [(3)H]BPB 1 equally bound to the head membranes from wild-type and dieldrin-resistant (rdl mutant) houseflies. GABA allosterically inhibited [(3)H]BPB 1 binding. By contrast, channel blocker-type antagonists enhanced [(3)H]BPB 1 binding to housefly head membranes by increasing the affinity of BPB 1. Antiparasitic macrolides, such as ivermectin B1a, were potent inhibitors of [(3)H]BPB 1 binding. BPB 1 inhibited GABA-induced currents in housefly GABARs expressed in Xenopus oocytes, whereas it failed to inhibit l-glutamate-induced currents in inhibitory l-glutamate receptors. Overall, these findings indicate that BPBs act at a novel allosteric site that is different from the site for channel blocker-type antagonists and that is probably overlapped with the site for macrolides in insect GABARs.
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Affiliation(s)
- Yoshihisa Ozoe
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan.
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18
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Kvist T, Greenwood JR, Hansen KB, Traynelis SF, Bräuner-Osborne H. Structure-based discovery of antagonists for GluN3-containing N-methyl-D-aspartate receptors. Neuropharmacology 2013; 75:324-36. [PMID: 23973313 DOI: 10.1016/j.neuropharm.2013.08.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [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: 03/04/2013] [Revised: 08/04/2013] [Accepted: 08/08/2013] [Indexed: 01/28/2023]
Abstract
NMDA receptors are ligand-gated ion channels that assemble into tetrameric receptor complexes composed of glycine-binding GluN1 and GluN3 subunits (GluN3A-B) and glutamate-binding GluN2 subunits (GluN2A-D). NMDA receptors can assemble as GluN1/N2 receptors and as GluN3-containing NMDA receptors, which are either glutamate/glycine-activated triheteromeric GluN1/N2/N3 receptors or glycine-activated diheteromeric GluN1/N3 receptors. The glycine-binding GluN1 and GluN3 subunits display strikingly different pharmacological selectivity profiles. However, the pharmacological characterization of GluN3-containing receptors has been hampered by the lack of methods and pharmacological tools to study GluN3 subunit pharmacology in isolation. Here, we have developed a method to study the pharmacology of GluN3 subunits in recombinant diheteromeric GluN1/N3 receptors by mutating the orthosteric ligand-binding pocket in GluN1. This method is suitable for performing compound screening and characterization of structure-activity relationship studies on GluN3 ligands. We have performed a virtual screen of the orthosteric binding site of GluN3A in the search for antagonists with selectivity for GluN3 subunits. In the subsequent pharmacological evaluation of 99 selected compounds, we identified 6-hydroxy-[1,2,5]oxadiazolo[3,4-b]pyrazin-5(4H)-one (TK80) a novel competitive antagonist with preference for the GluN3B subunit. Serendipitously, we also identified [2-hydroxy-5-((4-(pyridin-3-yl)thiazol-2-yl)amino]benzoic acid (TK13) and 4-(2,4-dichlorobenzoyl)-1H-pyrrole-2-carboxylic acid (TK30), two novel non-competitive GluN3 antagonists. These findings demonstrate that structural differences between the orthosteric binding site of GluN3 and GluN1 can be exploited to generate selective ligands.
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Affiliation(s)
- Trine Kvist
- Dept. of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark
| | | | - Kasper B Hansen
- Dept. of Pharmacology, Emory University School of Medicine, 5062 Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322, USA
| | - Stephen F Traynelis
- Dept. of Pharmacology, Emory University School of Medicine, 5062 Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322, USA
| | - Hans Bräuner-Osborne
- Dept. of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark.
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