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Aripaka SS, Mikkelsen JD. Anti-Inflammatory Effect of Alpha7 Nicotinic Acetylcholine Receptor Modulators on BV2 Cells. Neuroimmunomodulation 2020; 27:194-202. [PMID: 33657564 DOI: 10.1159/000513197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 11/12/2020] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE The development of neuroinflammation shares numerous risk factors and involves many complex interactions which contribute to disease pathology. An important cell type in neuroinflammation is the active microglia cell - the resident immune cell of the CNS. There is increasing need to understand how these pathways related to neuroinflammation work and how they can be regulated. Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated receptors and widely distributed in the brain. The α7 nAChR is a penta-homomeric receptor and is one of the nAChRs expressed in microglia. This study was first designed to characterize the effects of lipopolysaccharide (LPS) on BV2 culture cells, a cell line of murine microglia origin, on release of inflammatory markers and to characterize the inhibitory effects of α7 nAChR modulators in these cells. METHODS First, the BV2 cell cultures were functionally validated by exposing them to LPS for 4-24 h and then examining the release of tumor necrosis factor-alpha (TNF-α) using ELISA and nitric oxide (NO) release using the Griess assay, respectively. Next, α7 nAChR modulators with different pharmacological profiles were applied dose-dependently to study their effects on LPS-induced release of NO and TNF-α. RESULTS The time-course and dose-response curve revealed that LPS dose-dependently activated (EC50 = 2.5 ng/mL) BV2 cells releasing TNF-α at 4 h, followed by release of NO that occurred first at 8-h time point. The α7 nAChR subunit mRNA was identified in the BV2 cells. The pharmacology studies showed the α7 nAChR selective modulators NS6740 and TQS reduced NO and cytokine release from BV2 cell cultures. CONCLUSION We here identified the dose- and time-dependent effects of LPS in BV2 cell cultures on several inflammatory readouts and showed that α7 nAChR modulators with little or no ion channel activity inhibited this anti-inflammatory mechanism.
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Affiliation(s)
- Sanjay S Aripaka
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Jens D Mikkelsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark,
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Djemil S, Chen X, Zhang Z, Lee J, Rauf M, Pak DTS, Dzakpasu R. Activation of nicotinic acetylcholine receptors induces potentiation and synchronization within in vitro hippocampal networks. J Neurochem 2019; 153:468-484. [PMID: 31821553 DOI: 10.1111/jnc.14938] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 12/04/2019] [Accepted: 12/05/2019] [Indexed: 01/08/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are known to play a role in cognitive functions of the hippocampus, such as memory consolidation. Given that they conduct Ca2+ and are capable of regulating the release of glutamate and γ-aminobutyric acid (GABA) within the hippocampus, thereby shifting the excitatory-inhibitory ratio, we hypothesized that the activation of nAChRs will result in the potentiation of hippocampal networks and alter synchronization. We used nicotine as a tool to investigate the impact of activation of nAChRs on neuronal network dynamics in primary embryonic rat hippocampal cultures prepared from timed-pregnant Sprague-Dawley rats. We perturbed cultured hippocampal networks with increasing concentrations of bath-applied nicotine and performed network extracellular recordings of action potentials using a microelectrode array. We found that nicotine modulated network dynamics in a concentration-dependent manner; it enhanced firing of action potentials as well as facilitated bursting activity. In addition, we used pharmacological agents to determine the contributions of discrete nAChR subtypes to the observed network dynamics. We found that β4-containing nAChRs are necessary for the observed increases in spiking, bursting, and synchrony, while the activation of α7 nAChRs augments nicotine-mediated network potentiation but is not necessary for its manifestation. We also observed that antagonists of N-methyl-D-aspartate receptors (NMDARs) and group I metabotropic glutamate receptors (mGluRs) partially blocked the effects of nicotine. Furthermore, nicotine exposure promoted autophosphorylation of Ca2+ /calmodulin-dependent kinase II (CaMKII) and serine 831 phosphorylation of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunit GluA1. These results suggest that nicotinic receptors induce potentiation and synchronization of hippocampal networks and glutamatergic synaptic transmission. Findings from this work highlight the impact of cholinergic signaling in generating network-wide potentiation in the form of enhanced spiking and bursting dynamics that coincide with molecular correlates of memory such as increased phosphorylation of CaMKII and GluA1. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.
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Affiliation(s)
- Sarra Djemil
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, USA
| | - Xin Chen
- Department of Physics, Georgetown University, Washington, DC, USA
| | - Ziyue Zhang
- Department of Physics, Georgetown University, Washington, DC, USA
| | - Jisoo Lee
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, USA
| | - Mikael Rauf
- Department of Human Science, Georgetown University Medical Center, Washington, DC, USA
| | - Daniel T S Pak
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, USA.,Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC, USA
| | - Rhonda Dzakpasu
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, USA.,Department of Physics, Georgetown University, Washington, DC, USA.,Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC, USA
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Liu Q, Li M, Whiteaker P, Shi FD, Morley BJ, Lukas RJ. Attenuation in Nicotinic Acetylcholine Receptor α9 and α10 Subunit Double Knock-Out Mice of Experimental Autoimmune Encephalomyelitis. Biomolecules 2019; 9:E827. [PMID: 31817275 PMCID: PMC6995583 DOI: 10.3390/biom9120827] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/15/2019] [Accepted: 11/24/2019] [Indexed: 12/30/2022] Open
Abstract
Experimental autoimmune encephalomyelitis (EAE) is attenuated in nicotinic acetylcholine receptor (nAChR) α9 subunit knock-out (α9 KO) mice. However, protection is incomplete, raising questions about roles for related, nAChR α10 subunits in ionotropic or recently-revealed metabotropic contributions to effects. Here, we demonstrate reduced EAE severity and delayed onset of disease signs in nAChR α9/α10 subunit double knock-out (DKO) animals relative to effects in wild-type (WT) control mice. These effects are indistinguishable from contemporaneously-observed effects in nicotine-treated WT or in α9 KO mice. Immune cell infiltration into the spinal cord and brain, reactive oxygen species levels in vivo, and demyelination, mostly in the spinal cord, are reduced in DKO mice. Disease severity is not altered relative to WT controls in mice harboring a gain-of-function mutation in α9 subunits. These findings minimize the likelihood that additional deletion of nAChR α10 subunits impacts disease differently than α9 KO alone, whether through ionotropic, metabotropic, or alternative mechanisms. Moreover, our results provide further evidence of disease-exacerbating roles for nAChR containing α9 subunits (α9*-nAChR) in EAE inflammatory and autoimmune responses. This supports our hypothesis that α9*-nAChR or their downstream mediators are attractive targets for attenuation of inflammation and autoimmunity.
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Affiliation(s)
- Qiang Liu
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, AZ 85013, USA; (Q.L.); (M.L.); (P.W.); (F.-D.S.)
| | - Minshu Li
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, AZ 85013, USA; (Q.L.); (M.L.); (P.W.); (F.-D.S.)
| | - Paul Whiteaker
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, AZ 85013, USA; (Q.L.); (M.L.); (P.W.); (F.-D.S.)
| | - Fu-Dong Shi
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, AZ 85013, USA; (Q.L.); (M.L.); (P.W.); (F.-D.S.)
| | | | - Ronald J. Lukas
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, AZ 85013, USA; (Q.L.); (M.L.); (P.W.); (F.-D.S.)
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Marquart LA, Turner MW, McDougal OM. Qualitative Assay to Detect Dopamine Release by Ligand Action on Nicotinic Acetylcholine Receptors. Toxins (Basel) 2019; 11:toxins11120682. [PMID: 31757080 PMCID: PMC6949981 DOI: 10.3390/toxins11120682] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 11/14/2019] [Accepted: 11/18/2019] [Indexed: 11/16/2022] Open
Abstract
A pheochromocytoma of the rat adrenal medulla derived (a.k.a. PC12) cell-based assay for dopamine measurement by luminescence detection was customized for the qualitative evaluation of agonists and antagonists of nicotinic acetylcholine receptors (nAChRs). The assay mechanism begins with ligand binding to transmembrane nAChRs, altering ion flow into the cell and inducing dopamine release from the cell. Following release, dopamine is oxidized by monoamine oxidase generating hydrogen peroxide that catalyzes a chemiluminescence reaction involving luminol and horseradish peroxidase, thus producing a detectable response. Results are presented for the action of nAChR agonists (acetylcholine, nicotine, and cytisine), and antagonists (α-conotoxins (α-CTxs) MII, ImI, LvIA, and PeIA) that demonstrate a luminescence response correlating to the increase or decrease of dopamine release. A survey of cell growth and treatment conditions, including nerve growth factor, nicotine, ethanol, and temperature, led to optimal assay requirements to achieve maximal signal intensity and consistent response to ligand treatment. It was determined that PC12 cells treated with a combination of nerve growth factor and nicotine, and incubated at 37 °C, provided favorable results for a reduction in luminescence signal upon treatment of cells with α-CTxs. The PC12 assay is intended for use as a fast, efficient, and economic qualitative method to assess the bioactivity of molecules that act on nAChRs, in which testing of ligand-nAChR binding hypotheses and computational predictions can be validated. As a screening method for nAChR bioactivity, lead compounds can be assessed for their likelihood of exhibiting desired bioactivity prior to being subjected to more complex quantitative methods, such as electrophysiology or live animal studies.
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Affiliation(s)
- Leanna A. Marquart
- Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725, USA;
| | - Matthew W. Turner
- Biomolecular Sciences PhD Program, Boise State University, Boise, ID 83725, USA;
| | - Owen M. McDougal
- Biomolecular Sciences PhD Program, Boise State University, Boise, ID 83725, USA;
- Correspondence:
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Sushma, Mondal AC. Role of GPCR signaling and calcium dysregulation in Alzheimer's disease. Mol Cell Neurosci 2019; 101:103414. [PMID: 31655116 DOI: 10.1016/j.mcn.2019.103414] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/17/2019] [Accepted: 09/24/2019] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD), a late onset neurodegenerative disorder is characterized by the loss of memory, disordered cognitive function, caused by accumulation of amyloid-β (Aβ) peptide and neurofibrillary tangles (NFTs) in the neocortex and hippocampal brain area. Extensive research has been done on the findings of the disease etiology or pathological causes of aggregation of Aβ and hyperphosphorylation of tau protein without much promising results. Recently, calcium dysregulation has been reported to play an important role in the pathophysiology of AD. Calcium ion acts as one of the major secondary messengers, regulates many signaling pathways involved in cell survival, proliferation, differentiation, transcription and apoptosis. Calcium signaling is one of the major signaling pathways involved in the formation of memory, generation of energy and other physiological functions. It also can modulate function of many proteins upon binding. Dysregulation in calcium homeostasis leads to many physiological changes leading to neurodegenerative diseases including AD. In AD, GPCRs generate secondary messengers which regulate calcium homeostasis inside the cell and is reported to be disturbed in the pathological condition. Calcium channels and receptors present on the plasma membrane and intracellular organelle maintain calcium homeostasis through different signaling mechanisms. In this review, we have summarized the different calcium channels and receptors involved in calcium dysregulation which in turn play a critical role in the pathogenesis of AD. Understanding the role of calcium channels and GPCRs to maintain calcium homeostasis is an attempt to develop effective AD treatments.
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Affiliation(s)
- Sushma
- Laboratory of Cellular and Molecular Neurobiology, School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Amal Chandra Mondal
- Laboratory of Cellular and Molecular Neurobiology, School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India.
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Hirano T, Minagawa S, Furusawa Y, Yunoki T, Ikenaka Y, Yokoyama T, Hoshi N, Tabuchi Y. Growth and neurite stimulating effects of the neonicotinoid pesticide clothianidin on human neuroblastoma SH-SY5Y cells. Toxicol Appl Pharmacol 2019; 383:114777. [PMID: 31626844 DOI: 10.1016/j.taap.2019.114777] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 10/03/2019] [Accepted: 10/05/2019] [Indexed: 10/25/2022]
Abstract
Neonicotinoids are one of most widely used pesticides targeting nicotinic acetylcholine receptors (nAChRs) of insects. Recent epidemiological evidence revealed increasing amounts of neonicotinoids detected in human samples, raising the critical question of whether neonicotinoids affect human health. We investigated the effects of a neonicotinoid pesticide clothianidin (CTD) on human neuroblastoma SH-SY5Y cells as in vitro models of human neuronal cells. Cellular and functional effects of micromolar doses of CTD were evaluated by changes in cell growth, intracellular signaling activities and gene expression profiles. We examined further the effects of CTD on neuronal differentiation by measuring neurite outgrowth. Exposure to CTD (1-100 μM) significantly increased the number of cells within 24 h of culture. The nAChRs antagonists, mecamylamine and SR16584, inhibited this effect, suggesting human α3β4 nAChRs could be targets of neonicotinoids. We observed a transient intracellular calcium influx and increased phosphorylation of extracellular signal-regulated kinase 1/2 shortly after exposure to CTD. Transcriptome analysis revealed that CTD down-regulated genes involved in neuronal function (e.g., formation of filopodia and calcium ion influx) and morphology (e.g., axon guidance signaling and cytoskeleton signaling); these changes were reflected by a finding of increased neurite length during neuronal differentiation. These findings provide novel insight into the potential risks of neonicotinoids to the human nervous system.
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Affiliation(s)
- Tetsushi Hirano
- Life Science Research Center, University of Toyama, Toyama, Japan.
| | - Satsuki Minagawa
- Life Science Research Center, University of Toyama, Toyama, Japan
| | - Yukihiro Furusawa
- Department of Liberal Arts and Sciences, Toyama Prefectural University, Toyama, Japan
| | - Tatsuya Yunoki
- Department of Ophthalmology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Yoshinori Ikenaka
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido, Japan; Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Toshifumi Yokoyama
- Department of Animal Science, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Nobuhiko Hoshi
- Department of Animal Science, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Yoshiaki Tabuchi
- Life Science Research Center, University of Toyama, Toyama, Japan
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Soto CA, Du HC, Fox RG, Yang T, Hooson J, Anastasio NC, Gilbertson SR, Cunningham KA. In Vivo and In Vitro Analyses of Novel Peptidomimetic Disruptors for the Serotonin 5-HT 2C Receptor Interaction With Phosphatase and Tensin Homolog. Front Pharmacol 2019; 10:907. [PMID: 31507411 PMCID: PMC6716272 DOI: 10.3389/fphar.2019.00907] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/18/2019] [Indexed: 01/03/2023] Open
Abstract
Hypofunction of the serotonin (5-HT) 5-HT2C receptor (5-HT2CR) has been implicated in a variety of disorders including substance use disorders. As such, approaches to enhance 5-HT2CR signaling display therapeutic potential. In the present study, we show that disruption of the 5-HT2CR interaction with the protein phosphatase and tensin homolog (PTEN) via peptidomimetics enhances 5-HT2CR-mediating signaling in vitro and potentiates selective 5-HT2CR agonists in behavioral rodent models. Overall, the present study provides further evidence that 5-HT2CR activity can be modulated through an allosteric protein-protein interaction. This work provides the groundwork for the continued exploration of protein-protein interactions that can allosterically modulate this critical receptor and other important G protein-coupled receptors (GPCRs) for new therapeutic development through mechanisms that may display clinical utility.
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Affiliation(s)
- Claudia A Soto
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
| | - Huang-Chi Du
- Department of Chemistry, University of Houston, Houston, TX, United States
| | - Robert G Fox
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
| | - Taegyun Yang
- Department of Chemistry, University of Houston, Houston, TX, United States
| | - James Hooson
- Department of Chemistry, University of Houston, Houston, TX, United States
| | - Noelle C Anastasio
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
| | - Scott R Gilbertson
- Department of Chemistry, University of Houston, Houston, TX, United States
| | - Kathryn A Cunningham
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
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58
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Blunt CEW, Dougherty DA. Binding Interactions of NS6740, a Silent Agonist of the α7 Nicotinic Acetylcholine Receptor. Mol Pharmacol 2019; 96:212-218. [PMID: 31175182 DOI: 10.1124/mol.119.116244] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/28/2019] [Indexed: 11/22/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (nAChR) is a potential drug target for the treatment of a number of neurologic and inflammatory disorders. Silent agonists are an emerging class of drugs that bind to the receptor but do not open the channel. Instead they shift the receptor to a desensitized state. Silent agonists may be able to target a subset of α7 nAChR-mediated signaling processes. Here we use noncanonical amino acid mutagenesis to characterize the binding to α7 by the silent agonist 1,4-diazabicyclo[3.2.2]nonan-4-yl(5-(3-(trifluoromethyl)phenyl)furan-2-yl)methanone (NS6740). We find that, like α7 agonists, NS6740 forms a cation-π interaction with Y115 (TyrA). We also showed that NS6740 makes a novel hydrogen bond to TyrA. This interaction is necessary for the silent agonist activity of NS6740; when the hydrogen bond is blocked, silent agonist NS6740 converts to a conventional partial agonist and appreciably opens the channel in the absence of a positive allosteric modulator (EC50 150 nM). SIGNIFICANCE STATEMENT: Noncanonical amino acids were used to show that a hydrogen bond to tyrosine (Y115) is required for silent agonist activity of NS6740 at the α7 nicotinic acetylcholine receptor.
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Affiliation(s)
- Catriona E W Blunt
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
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Elkhatib SK, Case AJ. Autonomic regulation of T-lymphocytes: Implications in cardiovascular disease. Pharmacol Res 2019; 146:104293. [PMID: 31176794 DOI: 10.1016/j.phrs.2019.104293] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/22/2019] [Accepted: 05/31/2019] [Indexed: 12/20/2022]
Abstract
The nervous and immune systems both serve as essential assessors and regulators of physiological function. Recently, there has been a great interest in how the nervous and immune systems interact to modulate both physiological and pathological states. In particular, the autonomic nervous system has a direct line of communication with immune cells anatomically, and moreover, immune cells possess receptors for autonomic neurotransmitters. This circumstantial evidence is suggestive of a functional interplay between the two systems, and extensive research over the past few decades has demonstrated neurotransmitters such as the catecholamines (i.e. dopamine, norepinephrine, and epinephrine) and acetylcholine have potent immunomodulating properties. Furthermore, immune cells, particularly T-lymphocytes, have now been found to express the cellular machinery for both the synthesis and degradation of neurotransmitters, which suggests the ability for both autocrine and paracrine signaling from these cells independent of the nervous system. The details underlying the functional interplay of this complex network of neuroimmune communication are still unclear, but this crosstalk is suggestive of significant implications on the pathogenesis of a number of autonomic-dysregulated and inflammation-mediated diseases. In particular, it is widely accepted that numerous forms of cardiovascular diseases possess imbalanced autonomic tone as well as altered T-lymphocyte function, but a paucity of literature exists discussing the direct role of neurotransmitters in shaping the inflammatory microenvironment during the progression or therapeutic management of these diseases. This review seeks to provide a fundamental framework for this autonomic neuroimmune interaction within T-lymphocytes, as well as the implications this may have in cardiovascular diseases.
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Affiliation(s)
- Safwan K Elkhatib
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Adam J Case
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States.
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Water-soluble variant of human Lynx1 induces cell cycle arrest and apoptosis in lung cancer cells via modulation of α7 nicotinic acetylcholine receptors. PLoS One 2019; 14:e0217339. [PMID: 31150435 PMCID: PMC6544245 DOI: 10.1371/journal.pone.0217339] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 05/10/2019] [Indexed: 12/14/2022] Open
Abstract
Lynx1 is the first three-finger prototoxin found in the mammalian central nervous system. It is a GPI-anchored protein modulating nicotinic acetylcholine receptors (nAChRs) in the brain. Besides the brain, the Lynx1 protein was found in the lung and kidney. Endogenous Lynx1 controls the nicotine-induced up-regulation of the expression of α7 type nAChRs in lung adenocarcinoma A549 cells as well as the cell growth. Here, we analyzed the Lynx1 expression in the set of human epithelial cells. The Lynx1 expression both at the mRNA and protein level was detected in normal oral keratinocytes, and lung, colon, epidermal, and breast cancer cells, but not in embryonic kidney cells. Co-localization of Lynx1 with α7-nAChRs was revealed in a cell membrane for lung adenocarcinoma A549 and colon carcinoma HT-29 cells, but not for breast adenocarcinoma MCF-7 and epidermoid carcinoma A431 cells. The recombinant water-soluble variant of Lynx1 without a GPI-anchor (ws-Lynx1) inhibited the growth of A549 cells causing cell cycle arrest via modulation of α7-nAChRs and activation of different intracellular signaling cascades, including PKC/IP3, MAP/ERK, p38, and JNK pathways. A549 cells treatment with ws-Lynx1 resulted in phosphorylation of the proapoptotic tumor suppressor protein p53 and different kinases participated in the regulation of gene transcription, cell growth, adhesion, and differentiation. Externalization of phosphatidylserine, an early apoptosis marker, observed by flow cytometry, confirmed the induction of apoptosis in A549 cells upon the ws-Lynx1 treatment. Our data revealed the ability of ws-Lynx1 to regulate homeostasis of epithelial cancer cells.
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Lara CO, Burgos CF, Silva-Grecchi T, Muñoz-Montesino C, Aguayo LG, Fuentealba J, Castro PA, Guzmán JL, Corringer PJ, Yévenes GE, Moraga-Cid G. Large Intracellular Domain-Dependent Effects of Positive Allosteric Modulators on Glycine Receptors. ACS Chem Neurosci 2019; 10:2551-2559. [PMID: 30893555 DOI: 10.1021/acschemneuro.9b00050] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Glycine receptors (GlyRs) are members of the pentameric ligand-gated ionic channel family (pLGICs) and mediate fast inhibitory neurotransmission in the brain stem and spinal cord. The function of GlyRs can be modulated by positive allosteric modulators (PAMs). So far, it is largely accepted that both the extracellular (ECD) and transmembrane (TMD) domains constitute the primary target for many of these PAMs. On the other hand, the contribution of the intracellular domain (ICD) to the PAM effects on GlyRs remains poorly understood. To gain insight about the role of the ICD in the pharmacology of GlyRs, we examined the contribution of each domain using a chimeric receptor. Two chimeras were generated, one consisting of the ECD of the prokaryotic homologue Gloeobacter violaceus ligand-gated ion channel (GLIC) fused to the TMD of the human α1GlyR lacking the ICD (Lily) and a second with the ICD (Lily-ICD). The sensitivity to PAMs of both chimeric receptors was studied using electrophysiological techniques. The Lily receptor showed a significant decrease in the sensitivity to four recognized PAMs. Remarkably, the incorporation of the ICD into the Lily background was sufficient to restore the wild-type α1GlyR sensitivity to these PAMs. Based on these data, we can suggest that the ICD is necessary to form a pLGIC having full sensitivity to positive allosteric modulators.
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Affiliation(s)
- Cesar O. Lara
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - Carlos F. Burgos
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - Tiare Silva-Grecchi
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - Carola Muñoz-Montesino
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - Luis G. Aguayo
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - Jorge Fuentealba
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - Patricio A. Castro
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - Jose L. Guzmán
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | | | - Gonzalo E. Yévenes
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - Gustavo Moraga-Cid
- Departamento de Fisiologı́a, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
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Zakrzewicz A, Richter K, Zakrzewicz D, Siebers K, Damm J, Agné A, Hecker A, McIntosh JM, Chamulitrat W, Krasteva-Christ G, Manzini I, Tikkanen R, Padberg W, Janciauskiene S, Grau V. SLPI Inhibits ATP-Mediated Maturation of IL-1β in Human Monocytic Leukocytes: A Novel Function of an Old Player. Front Immunol 2019; 10:664. [PMID: 31019507 PMCID: PMC6458293 DOI: 10.3389/fimmu.2019.00664] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/11/2019] [Indexed: 12/17/2022] Open
Abstract
Interleukin-1β (IL-1β) is a potent, pro-inflammatory cytokine of the innate immune system that plays an essential role in host defense against infection. However, elevated circulating levels of IL-1β can cause life-threatening systemic inflammation. Hence, mechanisms controlling IL-1β maturation and release are of outstanding clinical interest. Secretory leukocyte protease inhibitor (SLPI), in addition to its well-described anti-protease function, controls the expression of several pro-inflammatory cytokines on the transcriptional level. In the present study, we tested the potential involvement of SLPI in the control of ATP-induced, inflammasome-dependent IL-1β maturation and release. We demonstrated that SLPI dose-dependently inhibits the ATP-mediated inflammasome activation and IL-1β release in human monocytic cells, without affecting the induction of pro-IL-1β mRNA by LPS. In contrast, the ATP-independent IL-1β release induced by the pore forming bacterial toxin nigericin is not impaired, and SLPI does not directly modulate the ion channel function of the human P2X7 receptor heterologously expressed in Xenopus laevis oocytes. In human monocytic U937 cells, however, SLPI efficiently inhibits ATP-induced ion-currents. Using specific inhibitors and siRNA, we demonstrate that SLPI activates the calcium-independent phospholipase A2β (iPLA2β) and leads to the release of a low molecular mass factor that mediates the inhibition of IL-1β release. Signaling involves nicotinic acetylcholine receptor subunits α7, α9, α10, and Src kinase activation and results in an inhibition of ATP-induced caspase-1 activation. In conclusion, we propose a novel anti-inflammatory mechanism induced by SLPI, which inhibits the ATP-dependent maturation and secretion of IL-1β. This novel signaling pathway might lead to development of therapies that are urgently needed for the prevention and treatment of systemic inflammation.
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Affiliation(s)
- Anna Zakrzewicz
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Center for Lung Research, Justus-Liebig-University Giessen, Giessen, Germany
| | - Katrin Richter
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Center for Lung Research, Justus-Liebig-University Giessen, Giessen, Germany
| | - Dariusz Zakrzewicz
- German Center for Lung Research, Faculty of Medicine, Institute of Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany
| | - Kathrin Siebers
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Center for Lung Research, Justus-Liebig-University Giessen, Giessen, Germany
| | - Jelena Damm
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Center for Lung Research, Justus-Liebig-University Giessen, Giessen, Germany
| | - Alisa Agné
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Center for Lung Research, Justus-Liebig-University Giessen, Giessen, Germany
| | - Andreas Hecker
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Center for Lung Research, Justus-Liebig-University Giessen, Giessen, Germany
| | - J Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, United States.,George E. Wahlen Veterans Affairs, Medical Center, Salt Lake City, UT, United States.,Department of Psychiatry, University of Utah, Salt Lake City, UT, United States
| | - Walee Chamulitrat
- Department of Internal Medicine IV, University Heidelberg Hospital, Heidelberg, Germany
| | - Gabriela Krasteva-Christ
- Faculty of Medicine, Institute of Anatomy and Cell Biology, Saarland University, Homburg, Germany
| | - Ivan Manzini
- Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, Giessen, Germany
| | - Ritva Tikkanen
- Faculty of Medicine, Institute of Biochemistry, Justus-Liebig-University, Giessen, Germany
| | - Winfried Padberg
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Center for Lung Research, Justus-Liebig-University Giessen, Giessen, Germany
| | - Sabina Janciauskiene
- Department of Respiratory Medicine, German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Veronika Grau
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Center for Lung Research, Justus-Liebig-University Giessen, Giessen, Germany
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Kulbatskii DS, Bychkov ML, Lyukmanova EN. Human Nicotinic Acetylcholine Receptors: Part I—Structure, Function, and Role in Neuromuscular Transmission and CNS Functioning. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2019. [DOI: 10.1134/s1068162018060043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Novel 5-(quinuclidin-3-ylmethyl)-1,2,4-oxadiazoles to investigate the activation of the α7 nicotinic acetylcholine receptor subtype: Synthesis and electrophysiological evaluation. Eur J Med Chem 2018; 160:207-228. [PMID: 30342362 DOI: 10.1016/j.ejmech.2018.10.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/28/2018] [Accepted: 10/08/2018] [Indexed: 01/17/2023]
Abstract
α7 nicotinic acetylcholine receptors (nAChRs) are relevant therapeutic targets for a variety of disorders including neurodegeneration, cognitive impairment, and inflammation. Although traditionally identified as an ionotropic receptor, the α7 subtype showed metabotropic-like functions, mainly linked to the modulation of immune responses. In the present work, we investigated the structure-activity relationships in a set of novel α7 ligands incorporating the 5-(quinuclidin-3-ylmethyl)-1,2,4-oxadiazole scaffold, i.e. derivatives 21a-34a and 21b-34b, aiming to identify the structural requirements able to preferentially trigger one of the two activation modes of this receptor subtype. The new compounds were characterized as partial and silent α7 nAChR agonists in electrophysiological assays, which allowed to assess the contribution of the different groups towards the final pharmacological profile. Overall, modifications of the selected structural backbone mainly afforded partial agonists, among them tertiary bases 27a-33a, whereas additional hydrogen-bond acceptor groups in permanently charged ligands, such as 29b and 31b, favored a silent desensitizing profile at the α7 nAChR.
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Liu W, Li MD. Insights Into Nicotinic Receptor Signaling in Nicotine Addiction: Implications for Prevention and Treatment. Curr Neuropharmacol 2018; 16:350-370. [PMID: 28762314 PMCID: PMC6018190 DOI: 10.2174/1570159x15666170801103009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 06/18/2017] [Accepted: 07/28/2017] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Nicotinic acetylcholine receptors (nAChRs) belong to the Cys-loop ligandgated ion-channel (LGIC) superfamily, which also includes the GABA, glycine, and serotonin receptors. Many nAChR subunits have been identified and shown to be involved in signal transduction on binding to them of either the neurotransmitter acetylcholine or exogenous ligands such as nicotine. The nAChRs are pentameric assemblies of homologous subunits surrounding a central pore that gates cation flux, and they are expressed at neuromuscular junctions throughout the nervous system. METHODS AND RESULTS Because different nAChR subunits assemble into a variety of pharmacologically distinct receptor subtypes, and different nAChRs are implicated in various physiological functions and pathophysiological conditions, nAChRs represent potential molecular targets for drug addiction and medical therapeutic research. This review intends to provide insights into recent advances in nAChR signaling, considering the subtypes and subunits of nAChRs and their roles in nicotinic cholinergic systems, including structure, diversity, functional allosteric modulation, targeted knockout mutations, and rare variations of specific subunits, and the potency and functional effects of mutations by focusing on their effects on nicotine addiction (NA) and smoking cessation (SC). Furthermore, we review the possible mechanisms of action of nAChRs in NA and SC based on our current knowledge. CONCLUSION Understanding these cellular and molecular mechanisms will lead to better translational and therapeutic operations and outcomes for the prevention and treatment of NA and other drug addictions, as well as chronic diseases, such as Alzheimer's and Parkinson's. Finally, we put forward some suggestions and recommendations for therapy and treatment of NA and other chronic diseases.
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Affiliation(s)
- Wuyi Liu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China.,School of Biological Sciences and Food Engineering, Fuyang Normal University, Fuyang, Anuhi 236041, China
| | - Ming D Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China.,Research Center for Air Pollution and Health, Zhejiang University, Hangzhou, China.,Institute of NeuroImmune Pharmacology, Seton Hall University, South Orange, NJ, United States
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Zoli M, Pucci S, Vilella A, Gotti C. Neuronal and Extraneuronal Nicotinic Acetylcholine Receptors. Curr Neuropharmacol 2018; 16:338-349. [PMID: 28901280 PMCID: PMC6018187 DOI: 10.2174/1570159x15666170912110450] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/08/2017] [Accepted: 09/03/2017] [Indexed: 02/08/2023] Open
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) belong to a super-family of Cys-loop ligand-gated ion chan-nels that respond to endogenous acetylcholine (ACh) or other cholinergic ligands. These receptors are also the targets of drugs such as nicotine (the main addictive agent delivered by cigarette smoke) and are involved in a variety of physiological and pathophysiological processes. Numerous studies have shown that the expression and/or function of nAChRs is com-promised in many neurological and psychiatric diseases. Furthermore, recent studies have shown that neuronal nAChRs are found in a large number of non-neuronal cell types in-cluding endothelial cells, glia, immune cells, lung epithelia and cancer cells where they regulate cell differentiation, prolifera-tion and inflammatory responses. The aim of this review is to describe the most recent findings concerning the structure and function of native nAChRs inside and outside the nervous system.
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Affiliation(s)
- Michele Zoli
- Department of Biomedical, Metabolic and Neural Sciences, Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Susanna Pucci
- CNR, Neuroscience Institute-Milano, Biometra University of Milan, Milan, Italy
| | - Antonietta Vilella
- Department of Biomedical, Metabolic and Neural Sciences, Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Cecilia Gotti
- CNR, Neuroscience Institute-Milano, Biometra University of Milan, Milan, Italy
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Wang D, Meng Q, Leech CA, Yepuri N, Zhang L, Holz GG, Wang C, Cooney RN. α7 Nicotinic Acetylcholine Receptor Regulates the Function and Viability of L Cells. Endocrinology 2018; 159:3132-3142. [PMID: 29992246 PMCID: PMC6456923 DOI: 10.1210/en.2018-00433] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 07/02/2018] [Indexed: 12/20/2022]
Abstract
Enteroendocrine L cells secrete the incretin hormone glucagon-like peptide-1 (GLP-1), and they also express the α7 nicotinic acetylcholine receptor (α7nAChR), which may regulate GLP-1 secretion. Here, GTS-21, a selective α7nAChR agonist, was used to examine the effect of α7nAChR activation in L-cell lines, mouse intestinal primary cell cultures, and C57BL/6 mice. GTS-21 stimulated GLP-1 secretion in vitro, and this effect was attenuated by an α7nAChR antagonist or by α7nAChR-specific small interfering RNA. Under in vitro cell culture conditions of glucotoxicity, GTS-21 restored GLP-1 secretion and improved L-cell viability while also acting in vivo to raise levels of circulating GLP-1 in mice. To assess potential signaling mechanisms underlying these actions of GTS-21, we first monitored Ca2+, cAMP, and phosphatidylinositol 3-kinase (PI3K) activity. As expected for a GLP-1 secretagogue promoting Ca2+ influx through α7nAChR cation channels, [Ca2+]i increased in response to GTS-21, but [cAMP]i was unchanged. Surprisingly, pharmacological inhibition of growth factor signaling pathways revealed that GTS-21 also acts on the PI3K-protein kinase B-mammalian target of rapamycin pathway to promote L-cell viability. Moreover, the Ca2+ chelator BAPTA-AM counteracted GTS-21‒stimulated PI3K activity, thereby indicating unexpected crosstalk of L-cell Ca2+ and growth factor signaling pathways. Collectively, these data demonstrate that α7nAChR activation enhances GLP-1 secretion by increasing levels of cytosolic Ca2+ while also revealing Ca2+- and PI3K-dependent processes of α7nAChR activation that promote L-cell survival.
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Affiliation(s)
- Dawei Wang
- Department of Intensive Care Unit, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
- Department of Surgery, SUNY Upstate Medical University, Syracuse, New York
| | - Qinghe Meng
- Department of Surgery, SUNY Upstate Medical University, Syracuse, New York
| | - Colin A Leech
- Department of Surgery, SUNY Upstate Medical University, Syracuse, New York
| | - Natesh Yepuri
- Department of Surgery, SUNY Upstate Medical University, Syracuse, New York
| | - Linlin Zhang
- Department of Surgery, SUNY Upstate Medical University, Syracuse, New York
| | - George G Holz
- Department of Medicine, SUNY Upstate Medical University, Syracuse, New York
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, New York
| | - Chunting Wang
- Department of Critical Care Medicine, Shandong Provincial Hospital, Shandong University, Jinan, Shandong Province, China
- Correspondence: Robert N. Cooney, MD, Department of Surgery, SUNY Upstate Medical University, 750 East Adams Street, Suite 8141, Syracuse, New York 13210. E-mail: ; or Chunting Wang, MD, Department of Critical Care Medicine, Shandong Provincial Hospital, Shandong University, 9677 Jing 10 Road, Jinan 250101, Shandong, China. E-mail:
| | - Robert N Cooney
- Department of Surgery, SUNY Upstate Medical University, Syracuse, New York
- Correspondence: Robert N. Cooney, MD, Department of Surgery, SUNY Upstate Medical University, 750 East Adams Street, Suite 8141, Syracuse, New York 13210. E-mail: ; or Chunting Wang, MD, Department of Critical Care Medicine, Shandong Provincial Hospital, Shandong University, 9677 Jing 10 Road, Jinan 250101, Shandong, China. E-mail:
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Quadri M, Bagdas D, Toma W, Stokes C, Horenstein NA, Damaj MI, Papke RL. The Antinociceptive and Anti-Inflammatory Properties of the α7 nAChR Weak Partial Agonist p-CF 3 N, N-diethyl- N'-phenylpiperazine. J Pharmacol Exp Ther 2018; 367:203-214. [PMID: 30111636 DOI: 10.1124/jpet.118.249904] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 08/13/2018] [Indexed: 12/13/2022] Open
Abstract
Chronic pain and inflammatory diseases can be regulated by complex mechanisms involving α7 nicotinic acetylcholine receptors (nAChRs), making this subtype a promising drug target for anti-inflammatory therapies. Recent evidence suggests that suchtreatment of inflammatory pain may rely on metabotropic-like rather than ionotropic activation of the α7 receptor subtype in non-neuronal cells. We previously identified para-trifluoromethyl (p-CF3) N,N-diethyl-N'-phenylpiperazinium (diEPP) iodide to be among the compounds classified as silent agonists, which are very weak α7 partial agonists that are able to induce positive allosteric modulator (PAM)-sensitive desensitization. Such drugs have been shown to selectively promote α7 ionotropic-independent functions. Therefore, we here further investigated the electrophysiological profile of p-CF3 diEPP and its in vivo antinociceptive activity using Xenopus oocytes expressing α7, α4β2, or α3β4 nAChRs. The evoked currents confirmed p-CF3 diEPP to be α7-selective with a maximal agonism 5% that of acetylcholine (ACh). Coapplication of p-CF3 diEPP with the type II PAM 4-naphthalene-1-yl-3a,4,5,9b-tetrahydro-3-H-cyclopenta[c]quinoline-8-sulfonic acid amide (TQS) produced desensitization that could be converted to PAM-potentiated currents, which at a negative holding potential were up to 13-fold greater than ACh controls. Voltage-dependence experiments indicated that channel block may limit both control ACh and TQS-potentiated responses. Although no p-CF3 diEPP agonist activity was detected for the heteromeric nAChRs, it was a noncompetitive antagonist of these receptors. The compound displayed remarkable antihyperalgesic and antiedema effects in in vivo assays. The antinociceptive activity was dose and time dependent. The anti-inflammatory components were sensitive to the α7-selective antagonist methyllycaconitine, which supports the idea that these effects are mediated by the α7 nAChR.
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Affiliation(s)
- Marta Quadri
- Departments of Pharmacology and Therapeutics (M.Q., C.S., R.L.P.) and Chemistry (M.Q., N.A.H.), University of Florida, Gainesville, Florida; and Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia (D.B., W.T., M.I.D.)
| | - Deniz Bagdas
- Departments of Pharmacology and Therapeutics (M.Q., C.S., R.L.P.) and Chemistry (M.Q., N.A.H.), University of Florida, Gainesville, Florida; and Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia (D.B., W.T., M.I.D.)
| | - Wisam Toma
- Departments of Pharmacology and Therapeutics (M.Q., C.S., R.L.P.) and Chemistry (M.Q., N.A.H.), University of Florida, Gainesville, Florida; and Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia (D.B., W.T., M.I.D.)
| | - Clare Stokes
- Departments of Pharmacology and Therapeutics (M.Q., C.S., R.L.P.) and Chemistry (M.Q., N.A.H.), University of Florida, Gainesville, Florida; and Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia (D.B., W.T., M.I.D.)
| | - Nicole A Horenstein
- Departments of Pharmacology and Therapeutics (M.Q., C.S., R.L.P.) and Chemistry (M.Q., N.A.H.), University of Florida, Gainesville, Florida; and Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia (D.B., W.T., M.I.D.)
| | - M Imad Damaj
- Departments of Pharmacology and Therapeutics (M.Q., C.S., R.L.P.) and Chemistry (M.Q., N.A.H.), University of Florida, Gainesville, Florida; and Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia (D.B., W.T., M.I.D.)
| | - Roger L Papke
- Departments of Pharmacology and Therapeutics (M.Q., C.S., R.L.P.) and Chemistry (M.Q., N.A.H.), University of Florida, Gainesville, Florida; and Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia (D.B., W.T., M.I.D.)
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Jackson A, Papke RL, Damaj MI. Pharmacological modulation of the α7 nicotinic acetylcholine receptor in a mouse model of mecamylamine-precipitated nicotine withdrawal. Psychopharmacology (Berl) 2018; 235:1897-1905. [PMID: 29549391 PMCID: PMC6015775 DOI: 10.1007/s00213-018-4879-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 03/08/2018] [Indexed: 12/26/2022]
Abstract
RATIONALE Recent preclinical data has implicated the α7 nicotinic acetylcholine receptor (nAChR) as a target in modulating nicotine reward. However, the role of the channel properties of the α7 nAChR in nicotine withdrawal is unknown. OBJECTIVES This study aimed to investigate the impact of α7 nAChR pharmacological modulation on mecamylamine-precipitated nicotine withdrawal behaviors in mice by using positive allosteric modulators (PAMs). METHODS The effect of the orthosteric α7 nAChR full agonist PNU282987 (1, 3, 9 mg/kg, s.c.), type I α7 PAM NS1738 (1 and 10 mg/kg; i.p.) and the type II α7 PAM PNU120596 (3 and 9 mg/kg, i.p.) on anxiety-like behavior, somatic signs, and hyperalgesia was measured in mice undergoing mecamylamine-precipitated nicotine withdrawal. Mice were infused with 24 mg/kg/day nicotine or saline for 14 days using s.c. osmotic minipumps. Nicotine withdrawal signs were precipitated upon administration of the non-selective nAChR antagonist mecamylamine (3.5 mg/kg, i.p.). RESULTS Anxiety-like behavior in nicotine withdrawn mice was only attenuated by PNU282987 in a dose-related fashion. Somatic signs were reduced by PNU282987 and NS1738. PNU120596 was the only compound that reversed precipitated nicotine withdrawal-induced hyperalgesia. CONCLUSIONS Taken together, our results suggest that modulation of the α7 nAChR can play important roles in mecamylamine-precipitated nicotine withdrawal behaviors in mice. In addition, the effects of PAMs in this study suggest that endogenous acetylcholine/choline tone is sufficient to attenuate some aspects of precipitated nicotine withdrawal. These findings highlight a beneficial effect of using α7 nAChR PAMs in some aspects of precipitated nicotine withdrawal.
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Affiliation(s)
- Asti Jackson
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA.
| | - Roger L. Papke
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267 Gainesville, FL 32610-0267
| | - M. Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond VA, USA
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King JR, Ullah A, Bak E, Jafri MS, Kabbani N. Ionotropic and Metabotropic Mechanisms of Allosteric Modulation of α7 Nicotinic Receptor Intracellular Calcium. Mol Pharmacol 2018; 93:601-611. [PMID: 29588343 PMCID: PMC11033947 DOI: 10.1124/mol.117.111401] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 03/23/2018] [Indexed: 12/13/2022] Open
Abstract
The pharmacological targeting of the α7 nicotinic acetylcholine receptor (α7) is a promising strategy in the development of new drugs for neurologic diseases. Because α7 receptors regulate cellular calcium, we investigated how the prototypical type II-positive allosteric modulator PNU120596 affects α7-mediated calcium signaling. Live imaging experiments show that PNU120596 augments ryanodine receptor-driven calcium-induced calcium release (CICR), inositol-induced calcium release (IICR), and phospholipase C activation by the α7 receptor. Both influx of calcium through the α7 nicotinic acetylcholine receptor (nAChR) channel as well as the binding of intracellular G proteins were involved in the effect of PNU120596 on intracellular calcium. This is evidenced by the findings that chelation of extracellular calcium, expression of α7D44A or α7345-348A mutant subunits, or blockade of calcium store release compromised the ability of PNU120596 to increase intracellular calcium transients generated by α7 ligand activation. Spatiotemporal stochastic modeling of calcium transient responses corroborates these results and indicates that α7 receptor activation enables calcium microdomains locally and to lesser extent in the distant cytosol. From the model, allosteric modulation of the receptor activates CICR locally via ryanodine receptors and augments IICR through enhanced calcium influx due to prolonged α7 nAChR opening. These findings provide a new mechanistic framework for understanding the effect of α7 receptor allosteric modulation on both local and global calcium dynamics.
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Affiliation(s)
- Justin R King
- Interdisciplinary Program in Neuroscience (J.R.K., M.S.J., N.K.) and School of Systems Biology (A.U., E.B., M.S.J., N.K.), George Mason University, Fairfax, Virginia
| | - Aman Ullah
- Interdisciplinary Program in Neuroscience (J.R.K., M.S.J., N.K.) and School of Systems Biology (A.U., E.B., M.S.J., N.K.), George Mason University, Fairfax, Virginia
| | - Ellen Bak
- Interdisciplinary Program in Neuroscience (J.R.K., M.S.J., N.K.) and School of Systems Biology (A.U., E.B., M.S.J., N.K.), George Mason University, Fairfax, Virginia
| | - M Saleet Jafri
- Interdisciplinary Program in Neuroscience (J.R.K., M.S.J., N.K.) and School of Systems Biology (A.U., E.B., M.S.J., N.K.), George Mason University, Fairfax, Virginia
| | - Nadine Kabbani
- Interdisciplinary Program in Neuroscience (J.R.K., M.S.J., N.K.) and School of Systems Biology (A.U., E.B., M.S.J., N.K.), George Mason University, Fairfax, Virginia
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Delgado-Vélez M, Lasalde-Dominicci JA. The Cholinergic Anti-Inflammatory Response and the Role of Macrophages in HIV-Induced Inflammation. Int J Mol Sci 2018; 19:ijms19051473. [PMID: 29772664 PMCID: PMC5983673 DOI: 10.3390/ijms19051473] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/11/2018] [Accepted: 04/29/2018] [Indexed: 12/20/2022] Open
Abstract
Macrophages are phagocytic immune cells that protect the body from foreign invaders and actively support the immune response by releasing anti- and proinflammatory cytokines. A seminal finding revolutionized the way macrophages are seen. The expression of the neuronal alpha7 nicotinic acetylcholine receptor (α7-nAChR) in macrophages led to the establishment of the cholinergic anti-inflammatory response (CAR) in which the activation of this receptor inactivates macrophage production of proinflammatory cytokines. This novel neuroimmune response soon began to emerge as a potential target to counteract inflammation during illness and infection states. Human immunodeficiency virus (HIV)-infected individuals suffer from chronic inflammation that persists even under antiretroviral therapy. Despite the CAR’s importance, few studies involving macrophages have been performed in the HIV field. Evidence demonstrates that monocyte-derived macrophages (MDMs) recovered from HIV-infected individuals are upregulated for α7-nAChR. Moreover, in vitro studies demonstrate that addition of an HIV viral constituent, gp120IIIB, to uninfected MDMs also upregulates the α7-nAChR. Importantly, contrary to what was expected, activation of upregulated α7-nAChRs in macrophages does not reduce inflammation, suggesting a CAR disruption. Although it is reasonable to consider this receptor as a pharmacological target, additional studies are necessary since its activity seems to differ from that observed in neurons.
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Affiliation(s)
- Manuel Delgado-Vélez
- Molecular Sciences Research Center, University of Puerto Rico, San Juan 00926, Puerto Rico.
| | - José A Lasalde-Dominicci
- Molecular Sciences Research Center, University of Puerto Rico, San Juan 00926, Puerto Rico.
- Department of Biology, University of Puerto Rico, Río Piedras Campus, San Juan 00931, Puerto Rico.
- Department of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan 00931, Puerto Rico.
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King JR, Kabbani N. Alpha 7 nicotinic receptors attenuate neurite development through calcium activation of calpain at the growth cone. PLoS One 2018; 13:e0197247. [PMID: 29768467 PMCID: PMC5955587 DOI: 10.1371/journal.pone.0197247] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/30/2018] [Indexed: 11/18/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (nAChR) is a ligand-gated ion channel that plays an important role in cellular calcium signaling contributing to synaptic development and plasticity, and is a key drug target for the treatment of neurodegenerative conditions such as Alzheimer's disease. Here we show that α7 nAChR mediated calcium signals in differentiating PC12 cells activate the proteolytic enzyme calpain leading to spectrin breakdown, microtubule retraction, and attenuation in neurite growth. Imaging in growth cones confirms that α7 activation decreases EB3 comet motility in a calcium dependent manner as demonstrated by the ability of α7 nAChR, ryanodine, or IP3 receptor antagonists to block the effect of α7 nAChR on growth. α7 nAChR mediated EB3 comet motility, spectrin breakdown, and neurite growth was also inhibited by the addition of the selective calpain blocker calpeptin and attenuated by the expression of an α7 subunit unable to bind Gαq and activate calcium store release. The findings indicate that α7 nAChRs regulate cytoskeletal dynamics through local calcium signals for calpain protease activity.
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Affiliation(s)
- Justin R. King
- School of Systems Biology, George Mason University, Fairfax, Virginia, United States of America
| | - Nadine Kabbani
- School of Systems Biology, George Mason University, Fairfax, Virginia, United States of America
- * E-mail:
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Kabbani N, Nichols RA. Beyond the Channel: Metabotropic Signaling by Nicotinic Receptors. Trends Pharmacol Sci 2018; 39:354-366. [PMID: 29428175 DOI: 10.1016/j.tips.2018.01.002] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 01/05/2018] [Accepted: 01/08/2018] [Indexed: 01/01/2023]
Abstract
The α7 nicotinic acetylcholine receptor (nAChR) is a ligand-gated ion channel (LGIC) that plays an important role in cellular calcium signaling and contributes to several neurological diseases. Agonist binding to the α7 nAChR induces fast channel activation followed by inactivation and prolonged desensitization while triggering long-lasting calcium signaling. These activities foster neurotransmitter release, synaptic plasticity, and somatodendritic regulation in the brain. We discuss here the ability of α7 nAChRs to operate in ionotropic (α7i) and metabotropic (α7m) modes, leading to calcium-induced calcium release (CICR) and G protein-associated inositol trisphosphate (IP3)-induced calcium release (IICR), respectively. Metabotropic activity extends the spatial and temporal aspects of calcium signaling by the α7 channel beyond its ionotropic limits, persisting into the desensitized state. Delineation of the ionotropic and metabotropic properties of the α7 nAChR will provide definitive indicators of moment-to-moment receptor functional status that will, in turn, spearhead new drug development.
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Affiliation(s)
- Nadine Kabbani
- School of Systems Biology, George Mason University, Manassas, VA 20110, USA.
| | - Robert A Nichols
- Department of Cell and Molecular Biology, University of Hawai'i at Manoa, Honolulu, HI 96813, USA
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74
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Williams WR. Cell signal transduction: hormones, neurotransmitters and therapeutic drugs relate to purine nucleotide structure. J Recept Signal Transduct Res 2018; 38:101-111. [PMID: 29402169 DOI: 10.1080/10799893.2018.1431279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Purine nucleotides transduce cell membrane receptor responses and modulate ion channel activity. This is accomplished through conformational change in the structure of nucleotides and cell membrane associated proteins. The aim of this study is to enhance our understanding of nucleotide dependence in regard to signal transduction events, drug action and pharmacological promiscuity. Nucleotides and ligand structures regulating Gα protein subunits, voltage- and ligand-gated ion channels are investigated for molecular similarity using a computational program. Results differentiate agonist and antagonist structures, identify molecular similarity within nucleotide and ligand structures and demonstrate the potential of ligands to regulate nucleotide conformational change. Relative molecular similarity within nucleotides and the ligands of the major receptor classes provides insight into mechanisms of receptor and ion channel regulation. The nucleotide template model has some merit as an initial screening tool in the study and comparison of drug and hormone structures.
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Affiliation(s)
- W R Williams
- a Faculty of Life Sciences & Education , University of South Wales , Cardiff , UK
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75
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Gaydukov AE, Balezina OP. CaMKII Is Involved in the Choline-Induced Downregulation of Acetylcholine Release in Mouse Motor Synapses. Acta Naturae 2017; 9:110-113. [PMID: 29340224 PMCID: PMC5762835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Indexed: 11/25/2022] Open
Abstract
We investigated the involvement of calcium-dependent enzymes, protein kinase C (PKC) and calcium-calmodulin-dependent protein kinase II (CaMKII), in the signaling pathway triggered by the activation of presynaptic alpha7-type nicotinic acetylcholine receptors by exogenous choline, leading to downregulation of the evoked acetylcholine (ACh) release in mouse motor synapses. Blockade of PKC with chelerythrine neither changed the evoked release of ACh by itself nor prevented the inhibitory effect of choline. The CaMKII blocker KN-62 did not affect synaptic activity but fully prevented the choline-induced downregulation of ACh release.
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Affiliation(s)
- A. E. Gaydukov
- Department of Human and Animal Physiology, Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, bldg. 12, Moscow, 119234, Russia
| | - O. P. Balezina
- Department of Human and Animal Physiology, Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, bldg. 12, Moscow, 119234, Russia
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76
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Quadri M, Stokes C, Gulsevin A, Felts ACJ, Abboud KA, Papke RL, Horenstein NA. Sulfonium as a Surrogate for Ammonium: A New α7 Nicotinic Acetylcholine Receptor Partial Agonist with Desensitizing Activity. J Med Chem 2017; 60:7928-7934. [PMID: 28885019 DOI: 10.1021/acs.jmedchem.7b00875] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Weak partial agonists that promote a desensitized state of the α7 nicotinic acetylcholine receptor (nAChR) have been associated with anti-inflammatory effects. Exemplar compounds feature a tertiary or quaternary ammonium group. We report the synthesis, structure, and electrophysiological evaluation of 1-ethyl-4-phenylthiomorpholin-1-ium triflate, a weak partial agonist with a sulfonium isostere of the ammonium pharmacophore. These results offer new insights in understanding nAChR-ligand interactions and provide a new chemical space to target the α7 nAChR.
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Affiliation(s)
- Marta Quadri
- Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611-7200, United States.,Department of Pharmacology and Therapeutics, University of Florida , P.O. Box 100267, Gainesville, Florida 32610, United States
| | - Clare Stokes
- Department of Pharmacology and Therapeutics, University of Florida , P.O. Box 100267, Gainesville, Florida 32610, United States
| | - Alican Gulsevin
- Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Ashley C J Felts
- Department of Chemistry, Center of X-Ray Crystallography, University of Florida , P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Khalil A Abboud
- Department of Chemistry, Center of X-Ray Crystallography, University of Florida , P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida , P.O. Box 100267, Gainesville, Florida 32610, United States
| | - Nicole A Horenstein
- Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611-7200, United States
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Fujii T, Mashimo M, Moriwaki Y, Misawa H, Ono S, Horiguchi K, Kawashima K. Expression and Function of the Cholinergic System in Immune Cells. Front Immunol 2017; 8:1085. [PMID: 28932225 PMCID: PMC5592202 DOI: 10.3389/fimmu.2017.01085] [Citation(s) in RCA: 217] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/21/2017] [Indexed: 12/29/2022] Open
Abstract
T and B cells express most cholinergic system components—e.g., acetylcholine (ACh), choline acetyltransferase (ChAT), acetylcholinesterase, and both muscarinic and nicotinic ACh receptors (mAChRs and nAChRs, respectively). Using ChATBAC-eGFP transgenic mice, ChAT expression has been confirmed in T and B cells, dendritic cells, and macrophages. Moreover, T cell activation via T-cell receptor/CD3-mediated pathways upregulates ChAT mRNA expression and ACh synthesis, suggesting that this lymphocytic cholinergic system contributes to the regulation of immune function. Immune cells express all five mAChRs (M1–M5). Combined M1/M5 mAChR-deficient (M1/M5-KO) mice produce less antigen-specific antibody than wild-type (WT) mice. Furthermore, spleen cells in M1/M5-KO mice produce less tumor necrosis factor (TNF)-α and interleukin (IL)-6, suggesting M1/M5 mAChRs are involved in regulating pro-inflammatory cytokine and antibody production. Immune cells also frequently express the α2, α5, α6, α7, α9, and α10 nAChR subunits. α7 nAChR-deficient (α7-KO) mice produce more antigen-specific antibody than WT mice, and spleen cells from α7-KO mice produce more TNF-α and IL-6 than WT cells. This suggests that α7 nAChRs are involved in regulating cytokine production and thus modulate antibody production. Evidence also indicates that nicotine modulates immune responses by altering cytokine production and that α7 nAChR signaling contributes to immunomodulation through modification of T cell differentiation. Together, these findings suggest the involvement of both mAChRs and nAChRs in the regulation of immune function. The observation that vagus nerve stimulation protects mice from lethal endotoxin shock led to the notion of a cholinergic anti-inflammatory reflex pathway, and the spleen is an essential component of this anti-inflammatory reflex. Because the spleen lacks direct vagus innervation, it has been postulated that ACh synthesized by a subset of CD4+ T cells relays vagal nerve signals to α7 nAChRs on splenic macrophages, which downregulates TNF-α synthesis and release, thereby modulating inflammatory responses. However, because the spleen is innervated solely by the noradrenergic splenic nerve, confirmation of an anti-inflammatory reflex pathway involving the spleen requires several more hypotheses to be addressed. We will review and discuss these issues in the context of the cholinergic system in immune cells.
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Affiliation(s)
- Takeshi Fujii
- Faculty of Pharmaceutical Sciences, Department of Pharmacology, Doshisha Women's College of Liberal Arts, Kyoto, Japan
| | - Masato Mashimo
- Faculty of Pharmaceutical Sciences, Department of Pharmacology, Doshisha Women's College of Liberal Arts, Kyoto, Japan
| | - Yasuhiro Moriwaki
- Faculty of Pharmacy, Department of Pharmacology, Keio University, Tokyo, Japan
| | - Hidemi Misawa
- Faculty of Pharmacy, Department of Pharmacology, Keio University, Tokyo, Japan
| | - Shiro Ono
- Laboratory of Immunology, Faculty of Pharmacy, Osaka Ohtani University, Osaka, Japan
| | - Kazuhide Horiguchi
- Department of Anatomy, Division of Medicine, University of Fukui Faculty of Medical Sciences, Fukui, Japan
| | - Koichiro Kawashima
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences, Tokyo, Japan
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King JR, Gillevet TC, Kabbani N. A G protein-coupled α7 nicotinic receptor regulates signaling and TNF-α release in microglia. FEBS Open Bio 2017; 7:1350-1361. [PMID: 28904864 PMCID: PMC5586346 DOI: 10.1002/2211-5463.12270] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 07/14/2017] [Indexed: 11/21/2022] Open
Abstract
Acetylcholine activation of α7 nicotinic acetylcholine receptors (α7 nAChRs) in microglia attenuates neuroinflammation and regulates TNF‐α release. We used lipopolysaccharide to model inflammation in the microglial cell line EOC20 and examined signaling by the α7 nAChR. Co‐immunoprecipitation experiments confirm that α7 nAChRs bind heterotrimeric G proteins in EOC20 cells. Interaction with Gαi mediates α7 nAChR signaling via enhanced intracellular calcium release and a decrease in cAMP, p38 phosphorylation, and TNF‐α release. These α7 nAChR effects were blocked by the inhibition of Gαi signaling via pertussis toxin, PLC activity with U73122, and α7 nAChR channel activity with the selective antagonist α‐bungarotoxin. Moreover, α7 nAChR signaling in EOC20 cells was significantly diminished by the expression of a dominant‐negative α7 nAChR, α7345‐8A, shown to be impaired in G protein binding. These findings indicate an essential role for G protein coupling in α7 nAChR function in microglia leading to the regulation of inflammation in the nervous system.
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Affiliation(s)
- Justin R King
- Interdisciplinary Program in Neuroscience Krasnow Institute for Advanced Study George Mason University Fairfax VA USA
| | - Trudy C Gillevet
- Interdisciplinary Program in Neuroscience Krasnow Institute for Advanced Study George Mason University Fairfax VA USA
| | - Nadine Kabbani
- School of Systems Biology Krasnow Institute for Advanced Study George Mason University Fairfax VA USA
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79
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Papke RL, Stokes C, Damaj MI, Thakur GA, Manther K, Treinin M, Bagdas D, Kulkarni AR, Horenstein NA. Persistent activation of α7 nicotinic ACh receptors associated with stable induction of different desensitized states. Br J Pharmacol 2017; 175:1838-1854. [PMID: 28477386 DOI: 10.1111/bph.13851] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 04/25/2017] [Accepted: 05/03/2017] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE GAT107 ((3aR,4S,9bS)-4-(4-bromo-phenyl)-3a,4,5,9b-tetrahydro-3H-cyclopenta-[c]quinoline-8-sulfonamide) is a positive allosteric modulator (PAM) and agonist of α7 nicotinic acetylcholine receptors (nAChRs)that can cause a prolonged period of primed potentiation of acetylcholine responses after drug washout. NS6740 is a silent agonist of α7 nAChRs that has little or no efficacy for activating the ion channel but induces stable desensitization states, some of which can be converted into channel-active states by PAMs. Although GAT107 and NS6740 appear to stably induce different non-conducting states, both agents are effective treatment for inflammation and inflammatory pain models. We sought to better understand how both of these drugs that have opposite effects on channel activation could regulate signal transduction. EXPERIMENTAL APPROACH Voltage-clamp experiments were conducted with α7 nAChRs expressed in Xenopus oocytes. KEY RESULTS Long-lived sensitivity to a PAM or to an agonist was produced by NS6740 or GAT107 respectively. With sequential applications, these two drugs induced varying levels of persistent activation, which is a unique condition for a receptor that is known for rapid desensitization. The non-conducting states induced by NS6740 or GAT107 differ in their sensitivity to an α7 nAChR-selective antagonist and in how effectively they promote current. CONCLUSIONS & IMPLICATIONS Our data suggest that the persistent currents represent a dynamic interconversion between different stable desensitized states and the PAM-inducible conducting states. However, the similarity of NS6740 and GAT107 effects on inflammation and pain suggests that the different stable non-conducting states have common activity on signal transduction. LINKED ARTICLES This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc.
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Affiliation(s)
- Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Clare Stokes
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - Ganesh A Thakur
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Khan Manther
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Millet Treinin
- Department of Medical Neurobiology, Hadassah Medical School, Hebrew University, Jerusalem, Israel
| | - Deniz Bagdas
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA.,Experimental Animals Breeding and Research Center, Faculty of Medicine, Uludag University, Bursa, Turkey
| | - Abhijit R Kulkarni
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
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80
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Crespi A, Colombo SF, Gotti C. Proteins and chemical chaperones involved in neuronal nicotinic receptor expression and function: an update. Br J Pharmacol 2017; 175:1869-1879. [PMID: 28294298 DOI: 10.1111/bph.13777] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 02/26/2017] [Accepted: 03/04/2017] [Indexed: 01/03/2023] Open
Abstract
Neuronal nicotinic ACh receptors (nAChRs) are a family of ACh-gated cation channels, and their homeostasis or proteostasis is essential for the correct physiology of the central and peripheral nervous systems. The proteostasis network regulates the folding, assembly, degradation and trafficking of nAChRs in order to ensure their efficient and functional expression at the cell surface. However, as nAChRs are multi-subunit, multi-span, integral membrane proteins, the folding and assembly is a very inefficient process, and only a small proportion of subunits can form functional pentamers. Moreover, the efficiency of assembly and trafficking varies widely depending on the nAChR subtypes and the cell type in which they are expressed. A detailed understanding of the mechanisms that regulate the functional expression of nAChRs in neurons and non-neuronal cells is therefore important. The purpose of this short review is to describe more recent findings concerning the chaperone proteins and target-specific and target-nonspecific pharmacological chaperones that modulate the expression of nAChR subtypes, and the possible mechanisms that underlie the dynamic changes of cell surface nAChRs. LINKED ARTICLES This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc.
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81
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Cook J, Zusi FC, McDonald IM, King D, Hill MD, Iwuagwu C, Mate RA, Fang H, Zhao R, Wang B, Cutrone J, Ma B, Gao Q, Knox RJ, Matchett M, Gallagher L, Ferrante M, Post-Munson D, Molski T, Easton A, Miller R, Jones K, Digavalli S, Healy F, Lentz K, Benitex Y, Clarke W, Natale J, Siuciak JA, Lodge N, Zaczek R, Denton R, Morgan D, Bristow LJ, Macor JE, Olson RE. Design and Synthesis of a New Series of 4-Heteroarylamino-1'-azaspiro[oxazole-5,3'-bicyclo[2.2.2]octanes as α7 Nicotinic Receptor Agonists. 1. Development of Pharmacophore and Early Structure-Activity Relationship. J Med Chem 2016; 59:11171-11181. [PMID: 27958732 DOI: 10.1021/acs.jmedchem.6b01506] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The design and synthesis of a series of quinuclidine-containing spirooxazolidines ("spiroimidates") and their utility as α7 nicotinic acetylcholine receptor partial agonists are described. Selected members of the series demonstrated excellent selectivity for α7 over the highly homologous 5-HT3A receptor. Modification of the N-spiroimidate heterocycle substituent led to (1S,2R,4S)-N-isoquinolin-3-yl)-4'H-4-azaspiro[bicyclo[2.2.2]octane-2,5'oxazol]-2'-amine (BMS-902483), a potent α7 partial agonist, which improved cognition in preclinical rodent models.
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Affiliation(s)
- James Cook
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - F Christopher Zusi
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Ivar M McDonald
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Dalton King
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Matthew D Hill
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Christiana Iwuagwu
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Robert A Mate
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Haiquan Fang
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Rulin Zhao
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Bei Wang
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Jingfang Cutrone
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Baoqing Ma
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Qi Gao
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Ronald J Knox
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Michele Matchett
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Lizbeth Gallagher
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Meredith Ferrante
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Debra Post-Munson
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Thaddeus Molski
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Amy Easton
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Regina Miller
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Kelli Jones
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Siva Digavalli
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Francine Healy
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Kimberley Lentz
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Yulia Benitex
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Wendy Clarke
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Joanne Natale
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Judith A Siuciak
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Nicholas Lodge
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Robert Zaczek
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Rex Denton
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Daniel Morgan
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Linda J Bristow
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - John E Macor
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Richard E Olson
- Research and Development, Bristol-Myers Squibb , 5 Research Parkway, Wallingford, Connecticut 06492, United States
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82
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Vulfius CA, Spirova EN, Serebryakova MV, Shelukhina IV, Kudryavtsev DS, Kryukova EV, Starkov VG, Kopylova NV, Zhmak MN, Ivanov IA, Kudryashova KS, Andreeva TV, Tsetlin VI, Utkin YN. Peptides from puff adder Bitis arietans venom, novel inhibitors of nicotinic acetylcholine receptors. Toxicon 2016; 121:70-76. [PMID: 27576061 DOI: 10.1016/j.toxicon.2016.08.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 07/19/2016] [Accepted: 08/25/2016] [Indexed: 11/17/2022]
Abstract
Phospholipase A2 (named bitanarin) possessing capability to block nicotinic acetylcholine receptors (nAChRs) was isolated earlier (Vulfius et al., 2011) from puff adder Bitis arietans venom. Further studies indicated that low molecular weight fractions of puff adder venom inhibit nAChRs as well. In this paper, we report on isolation from this venom and characterization of three novel peptides called baptides 1, 2 and 3 that reversibly block nAChRs. To isolate the peptides, the venom of B. arietans was fractionated by gel-filtration and reversed phase chromatography. The amino acid sequences of peptides were established by de novo sequencing using MALDI mass spectrometry. Baptide 1 comprised 7, baptides 2 and 3-10 amino acid residues, the latter being acetylated at the N-terminus. This is the first indication for the presence of such post-translational modification in snake venom proteins. None of the peptides contain cysteine residues. For biological activity studies the peptides were prepared by solid phase peptide synthesis. Baptide 3 and 2 blocked acetylcholine-elicited currents in isolated Lymnaea stagnalis neurons with IC50 of about 50 μM and 250 μM, respectively. In addition baptide 2 blocked acetylcholine-induced currents in muscle nAChR heterologously expressed in Xenopus oocytes with IC50 of about 3 μM. The peptides did not compete with radioactive α-bungarotoxin for binding to Torpedo and α7 nAChRs at concentration up to 200 μM that suggests non-competitive mode of inhibition. Calcium imaging studies on α7 and muscle nAChRs heterologously expressed in mouse neuroblastoma Neuro2a cells showed that on α7 receptor baptide 2 inhibited acetylcholine-induced increasing intracellular calcium concentration with IC50 of 20.6 ± 3.93 μM. On both α7 and muscle nAChRs the suppression of maximal response to acetylcholine by about 50% was observed at baptide 2 concentration of 25 μM, the value being close to IC50 on α7 nAChR. These data are in accord with non-competitive inhibition as follows from α-bungarotoxin binding experiments. The described peptides are the shortest peptides without disulfide bridges isolated from animal venom and capable to inhibit nAChR by non-competitive way.
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Affiliation(s)
- Catherine A Vulfius
- Institute of Cell Biophysics, Russian Academy of Sciences, Ul. Institutskaya 3, Pushchino Moscow Region, 142290, Russia
| | - Ekaterina N Spirova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Marina V Serebryakova
- Belozersky Institute for Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Irina V Shelukhina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Denis S Kudryavtsev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Elena V Kryukova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Vladislav G Starkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Nina V Kopylova
- Moscow State Pedagogical University, Ul. M. Pirogovskaya 1/1, Moscow, 119991, Russia
| | - Maxim N Zhmak
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia; OOO Syneuro, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Igor A Ivanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Ksenia S Kudryashova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Tatyana V Andreeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Victor I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Yuri N Utkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia.
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King JR, Kabbani N. Alpha 7 nicotinic receptor coupling to heterotrimeric G proteins modulates RhoA activation, cytoskeletal motility, and structural growth. J Neurochem 2016; 138:532-45. [DOI: 10.1111/jnc.13660] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/27/2016] [Accepted: 05/06/2016] [Indexed: 12/26/2022]
Affiliation(s)
- Justin R. King
- Department of Molecular Neuroscience; Krasnow Institute for Advanced Study; George Mason University; Fairfax Virginia USA
| | - Nadine Kabbani
- Department of Molecular Neuroscience; Krasnow Institute for Advanced Study; George Mason University; Fairfax Virginia USA
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84
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Zanetti SR, Ziblat A, Torres NI, Zwirner NW, Bouzat C. Expression and Functional Role of α7 Nicotinic Receptor in Human Cytokine-stimulated Natural Killer (NK) Cells. J Biol Chem 2016; 291:16541-52. [PMID: 27284006 DOI: 10.1074/jbc.m115.710574] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Indexed: 12/18/2022] Open
Abstract
The homomeric α7 nicotinic receptor (nAChR) is one of the most abundant nAChRs in the central nervous system where it contributes to cognition, attention, and working memory. α7 nAChR is also present in lymphocytes, dendritic cells (DCs), and macrophages and it is emerging as an important drug target for intervention in inflammation and sepsis. Natural killer (NK) cells display cytotoxic activity against susceptible target cells and modulate innate and adaptive immune responses through their interaction with DCs. We here show that human NK cells also express α7 nAChR. α7 nAChR mRNA is detected by RT-PCR and cell surface expression of α7 nAChR is detected by confocal microscopy and flow cytometry using α-bungarotoxin, a specific antagonist. Both mRNA and protein levels increase during NK stimulation with cytokines (IL-12, IL-18, and IL-15). Exposure of cytokine-stimulated NK cells to PNU-282987, a specific α7 nAChR agonist, increases intracellular calcium concentration ([Ca(2+)]i) mainly released from intracellular stores, indicating that α7 nAChR is functional. Moreover, its activation by PNU-282987 plus a specific positive allosteric modulator greatly enhances the Ca(2+) responses in NK cells. Stimulation of NK cells with cytokines and PNU-282987 decreases NF-κB levels and nuclear mobilization, down-regulates NKG2D receptors, and decreases NKG2D-dependent cell-mediated cytotoxicity and IFN-γ production. Also, such NK cells are less efficient to trigger DC maturation. Thus, our results demonstrate the anti-inflammatory role of α7 nAChR in NK cells and suggest that modulation of its activity in these cells may constitute a novel target for regulation of the immune response.
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Affiliation(s)
- Samanta R Zanetti
- From the Instituto de Investigaciones Bioquímicas (INIBIBB), Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000 Bahía Blanca
| | - Andrea Ziblat
- the Instituto de Biología y Medicina Experimental, CONICET, C1428ADN-Ciudad de Buenos Aires, and
| | - Nicolás I Torres
- the Instituto de Biología y Medicina Experimental, CONICET, C1428ADN-Ciudad de Buenos Aires, and
| | - Norberto W Zwirner
- the Instituto de Biología y Medicina Experimental, CONICET, C1428ADN-Ciudad de Buenos Aires, and the Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428ADN-Ciudad de Buenos Aires, Argentina
| | - Cecilia Bouzat
- From the Instituto de Investigaciones Bioquímicas (INIBIBB), Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000 Bahía Blanca,
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85
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Corradi J, Bouzat C. Understanding the Bases of Function and Modulation of α7 Nicotinic Receptors: Implications for Drug Discovery. Mol Pharmacol 2016; 90:288-99. [PMID: 27190210 DOI: 10.1124/mol.116.104240] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/05/2016] [Indexed: 01/01/2023] Open
Abstract
The nicotinic acetylcholine receptor (nAChR) belongs to a superfamily of pentameric ligand-gated ion channels involved in many physiologic and pathologic processes. Among nAChRs, receptors comprising the α7 subunit are unique because of their high Ca(2+) permeability and fast desensitization. nAChR agonists elicit a transient ion flux response that is further sustained by the release of calcium from intracellular sources. Owing to the dual ionotropic/metabotropic nature of α7 receptors, signaling pathways are activated. The α7 subunit is highly expressed in the nervous system, mostly in regions implicated in cognition and memory and has therefore attracted attention as a novel drug target. Additionally, its dysfunction is associated with several neuropsychiatric and neurologic disorders, such as schizophrenia and Alzheimer's disease. α7 is also expressed in non-neuronal cells, particularly immune cells, where it plays a role in immunity, inflammation, and neuroprotection. Thus, α7 potentiation has emerged as a therapeutic strategy for several neurologic and inflammatory disorders. With unique activation properties, the receptor is a sensitive drug target carrying different potential binding sites for chemical modulators, particularly agonists and positive allosteric modulators. Although macroscopic and single-channel recordings have provided significant information about the underlying molecular mechanisms and binding sites of modulatory compounds, we know just the tip of the iceberg. Further concerted efforts are necessary to effectively exploit α7 as a drug target for each pathologic situation. In this article, we focus mainly on the molecular basis of activation and drug modulation of α7, key pillars for rational drug design.
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Affiliation(s)
- Jeremías Corradi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur, CONICET/UNS, Bahía Blanca, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur, CONICET/UNS, Bahía Blanca, Argentina
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Horenstein NA, Papke RL, Kulkarni AR, Chaturbhuj GU, Stokes C, Manther K, Thakur GA. Critical Molecular Determinants of α7 Nicotinic Acetylcholine Receptor Allosteric Activation: SEPARATION OF DIRECT ALLOSTERIC ACTIVATION AND POSITIVE ALLOSTERIC MODULATION. J Biol Chem 2016; 291:5049-67. [PMID: 26742843 DOI: 10.1074/jbc.m115.692392] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Indexed: 01/08/2023] Open
Abstract
The α7 nicotinic acetylcholine receptors (nAChRs) are uniquely sensitive to selective positive allosteric modulators (PAMs), which increase the efficiency of channel activation to a level greater than that of other nAChRs. Although PAMs must work in concert with "orthosteric" agonists, compounds such as GAT107 ((3aR,4S,9bS)-4-(4-bromophenyl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinoline-8-sulfonamide) have the combined properties of agonists and PAMs (ago-PAM) and produce very effective channel activation (direct allosteric activation (DAA)) by operating at two distinct sites in the absence of added agonist. One site is likely to be the same transmembrane site where PAMs like PNU-120596 function. We show that the other site, required for direct activation, is likely to be solvent-accessible at the extracellular domain vestibule. We identify key attributes of molecules in this family that are able to act at the DAA site through variation at the aryl ring substituent of the tetrahydroquinoline ring system and with two different classes of competitive antagonists of DAA. Analyses of molecular features of effective allosteric agonists allow us to propose a binding model for the DAA site, featuring a largely non-polar pocket accessed from the extracellular vestibule with an important role for Asp-101. This hypothesis is supported with data from site-directed mutants. Future refinement of the model and the characterization of specific GAT107 analogs will allow us to define critical structural elements that can be mapped onto the receptor surface for an improved understanding of this novel way to target α7 nAChR therapeutically.
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Affiliation(s)
- Nicole A Horenstein
- From the Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200
| | - Roger L Papke
- the Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida 32610-0267, and
| | - Abhijit R Kulkarni
- the Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115
| | - Ganesh U Chaturbhuj
- the Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115
| | - Clare Stokes
- the Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida 32610-0267, and
| | - Khan Manther
- the Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida 32610-0267, and
| | - Ganesh A Thakur
- the Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115
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