1
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Pacheco PAF, Faria JV, Silva AC, von Ranke NL, Silva RC, Rodrigues CR, da Rocha DR, Faria RX. In silico and pharmacological study of N,S-acetal juglone derivatives as inhibitors of the P2X7 receptor-promoted in vitro and in vivo inflammatory response. Biomed Pharmacother 2023; 162:114608. [PMID: 37003033 DOI: 10.1016/j.biopha.2023.114608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/23/2023] [Accepted: 03/24/2023] [Indexed: 04/01/2023] Open
Abstract
Purinergic receptors are transmembrane proteins responsive to extracellular nucleotides and are expressed by several cell types throughout the human body. Among all identified subtypes, the P2×7 receptor has emerged as a relevant target for the treatment of inflammatory disease. Several clinical trials have been conducted to evaluate the effectiveness of P2×7R antagonists. However, to date, no selective antagonist has reached clinical use. In this work, we report the pharmacological evaluation of eleven N, S-acetal juglone derivatives as P2×7R inhibitors. Using in vitro assays and in vivo experimental models, we identified one derivative with promising inhibitory activity and low toxicity. Our in silico studies indicate that the 1,4-naphthoquinone moiety might be a valuable molecular scaffold for the development of novel P2×7R antagonists, as suggested by our previous studies.
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2
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Toti KS, Verma R, McGonnigle MJ, Gamiotea Turro D, Wen Z, Lewicki SA, Liang BT, Jacobson KA. Structure-Activity Relationship and Neuroprotective Activity of 1,5-Dihydro-2 H-naphtho[1,2- b][1,4]diazepine-2,4(3 H)-diones as P2X4 Receptor Antagonists. J Med Chem 2022; 65:13967-13987. [PMID: 36150180 PMCID: PMC9653265 DOI: 10.1021/acs.jmedchem.2c01197] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We analyzed the P2X4 receptor structure-activity relationship of a known antagonist 5, a 1,5-dihydro-2H-naphtho[1,2-b][1,4]diazepine-2,4(3H)-dione. Following extensive modification of the reported synthetic route, 4-pyridyl 21u (MRS4719) and 6-methyl 22c (MRS4596) analogues were most potent at human (h) P2X4R (IC50 0.503 and 1.38 μM, respectively, and selective versus hP2X1R, hP2X2/3R, hP2X3R). Thus, the naphthalene 6-, but not 7-position was amenable to substitution, and an N-phenyl ring aza-scan identified 21u with 3-fold higher activity than 5. Compounds 21u and 22c showed neuroprotective and learning- and memory-enhancing activities in a mouse middle cerebral artery occlusion (MCAO) model of ischemic stroke, with potency of 21u > 22c. 21u dose-dependently reduced infarct volume and reduced brain atrophy at 3 and 35 days post-stroke, respectively. Relevant to clinical implication, 21u also reduced ATP-induced [Ca2+]i influx in primary human monocyte-derived macrophages. This study indicates the translational potential of P2X4R antagonists for treating ischemic stroke, including in aging populations.
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Affiliation(s)
- Kiran S Toti
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892-0810, United States
| | - Rajkumar Verma
- Department of Neuroscience, UConn School of Medicine, Farmington, Connecticut 06032, United States
| | - Michael J McGonnigle
- Department of Neuroscience, UConn School of Medicine, Farmington, Connecticut 06032, United States
| | - Daylin Gamiotea Turro
- Department of Neuroscience, UConn School of Medicine, Farmington, Connecticut 06032, United States
| | - Zhiwei Wen
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892-0810, United States
| | - Sarah A Lewicki
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892-0810, United States
| | - Bruce T Liang
- Calhoun Cardiology Center, UConn School of Medicine, Farmington, Connecticut 06032, United States
| | - Kenneth A Jacobson
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892-0810, United States
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3
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Nadzirin IB, Fortuny-Gomez A, Ngum N, Richards D, Ali S, Searcey M, Fountain SJ. Taspine is a natural product that suppresses P2X4 receptor activity via phosphoinositide 3-kinase inhibition. Br J Pharmacol 2021; 178:4859-4872. [PMID: 34398973 DOI: 10.1111/bph.15663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 07/28/2021] [Accepted: 08/03/2021] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND & PURPOSE P2X4 is a ligand-gated cation channel activated by extracellular ATP, involved in neuropathic pain, inflammation and arterial tone. EXPERIMENTAL APPROACH Natural products were screened against human or mouse P2X4 activity using fura-2 loaded 1321N1 cells for measurement of intracellular Ca2+ responses; whole-cell currents were measured by patch clamp electrophysiological. Human primary macrophage chemokine release was used to assess effect of taspine on inflammatory cell function. An enzymatic assay was performed to assess the effect of taspine on recombinant PI3-kinase. KEY RESULTS A natural product screen identified taspine as an inhibitor of human P2X4 activity. Taspine inhibits human and mouse P2X4-mediated Ca2+ influx in 1321N1 cells expressing receptors (IC50 1.6±0.4 μM and 1.6±0.3 μM, respectively), but lacked activity at human P2X2, P2X3, P2X2/3 and P2X7 receptors. Taspine inhibited the maximal response at human and mouse P2X4 but had no effect on ATP potency. Taspine has a slow onset rate (~15 mins for half-maximal inhibition), irreversible over 30 minutes of washout. Taspine inhibits P2X4-mediated Ca2+ signalling in mouse BV-2 microglia cells and human primary macrophage. Taspine inhibited P2X4-mediated CXCL5 secretion in human primary macrophage. Taspine reversed ivermectin-induced potentiation of P2X4 currents in 1321N1 stably expressing cells. The known PI3-kinase inhibitor LY294002 mimicked the properties of taspine on P2X4-mediated Ca2+ influx and whole-cell currents. Taspine directly inhibited the enzymatic activity of recombinant PI3-kinase in a competitive manner. CONCLUSIONS AND IMPLICATIONS Taspine is a novel natural product P2X4 inhibitor, mediating its effect through PI3-kinase inhibitor rather than receptor antagonism. Taspine can inhibit the pro-inflammatory signalling by P2X4 in human primary macrophage.
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Affiliation(s)
- Izzuddin Bin Nadzirin
- Biomedical Research Centre, School of Biological Sciences, University of East Anglia, Norwich Research Park.,Kulliyyah of Allied Health Sciences, International Islamic University Malaysia, Kuantan Campus, Kuantan, Malaysia
| | - Anna Fortuny-Gomez
- Biomedical Research Centre, School of Biological Sciences, University of East Anglia, Norwich Research Park
| | - Neville Ngum
- Biomedical Research Centre, School of Biological Sciences, University of East Anglia, Norwich Research Park
| | - David Richards
- Biomedical Research Centre, School of Biological Sciences, University of East Anglia, Norwich Research Park
| | - Seema Ali
- Biomedical Research Centre, School of Biological Sciences, University of East Anglia, Norwich Research Park
| | - Mark Searcey
- School of Pharmacy, University of East Anglia, Norwich Research Park
| | - Samuel J Fountain
- Biomedical Research Centre, School of Biological Sciences, University of East Anglia, Norwich Research Park
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4
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Peralta FA, Huidobro-Toro JP, Mera-Adasme R. Hybrid QM/MM Simulations Confirm Zn(II) Coordination Sphere That Includes Four Cysteines from the P2 × 4R Head Domain. Int J Mol Sci 2021; 22:ijms22147288. [PMID: 34298909 PMCID: PMC8303255 DOI: 10.3390/ijms22147288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 11/21/2022] Open
Abstract
To ascertain the role of Zn(II) as an allosteric modulator on P2X4R, QM/MM molecular dynamic simulations were performed on the WT and two P2X4R mutants suggested by previous electrophysiological data to affect Zn(II) binding. The Gibbs free energy for the reduction of the putative P2X4R Zn(II) binding site by glutathione was estimated at −22 kcal/mol. Simulations of the WT P2X4R head domain revealed a flexible coordination sphere dominated by an octahedral geometry encompassing C126, N127, C132, C149, C159 and a water molecule. The C132A mutation disrupted the metal binding site, leading to a coordination sphere with a majority of water ligands, and a displacement of the metal ion towards the solvent. The C132A/C159A mutant exhibited a tendency towards WT-like stability by incorporating the R148 backbone to the coordination sphere. Thus, the computational findings agree with previous experimental data showing Zn(II) modulation for the WT and C132A/C159A variants, but not for the C132A mutant. The results provide molecular insights into the nature of the Zn(II) modulation in P2X4R, and the effect of the C132A and C132A/C159A mutations, accounting for an elusive modulation mechanism possibly occurring in other extracellular or membrane protein.
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Affiliation(s)
| | - J. Pablo Huidobro-Toro
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile (USACH), Santiago 9170124, Chile
- Centro Para el Desarrollo de Nanociencia y Nanotecnología, (CEDENNA), Universidad de Santiago de Chile (USACH), Santiago 9170124, Chile
- Correspondence: (J.P.H.-T.); (R.M.-A.)
| | - Raúl Mera-Adasme
- Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile (USACH), Santiago 9170124, Chile
- Correspondence: (J.P.H.-T.); (R.M.-A.)
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5
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Zhang L, Wang H. FTY720 in CNS injuries: Molecular mechanisms and therapeutic potential. Brain Res Bull 2020; 164:75-82. [DOI: 10.1016/j.brainresbull.2020.08.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 05/23/2020] [Accepted: 08/15/2020] [Indexed: 12/25/2022]
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6
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New Insights of the Zn(II)-Induced P2 × 4R Positive Allosteric Modulation: Role of Head Receptor Domain SS2/SS3, E160 and D170. Int J Mol Sci 2020; 21:ijms21186940. [PMID: 32971737 PMCID: PMC7555825 DOI: 10.3390/ijms21186940] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 07/23/2020] [Accepted: 07/30/2020] [Indexed: 01/18/2023] Open
Abstract
P2 × 4R is allosterically modulated by Zn(II), and despite the efforts to understand the mechanism, there is not a consensus proposal; C132 is a critical amino acid for the Zn(II) modulation, and this residue is located in the receptor head domain, forming disulfide SS3. To ascertain the role of the SS2/SS3 microenvironment on the rP2 × 4R Zn(II)-induced allosteric modulation, we investigated the contribution of each individual SS2/SS3 cysteine plus carboxylic acid residues E118, E160, and D170, located in the immediate vicinity of the SS2/SS3 disulfide bonds. To this aim, we combined electrophysiological recordings with protein chemical alkylation using thiol reagents such as N-ethylmaleimide or iodoacetamide, and a mutation of key amino acid residues together with P2 × 4 receptor bioinformatics. P2 × 4R alkylation in the presence of the metal obliterated the allosteric modulation, a finding supported by the site-directed mutagenesis of C132 and C149 by a corresponding alanine. In addition, while E118Q was sensitive to Zn(II) modulation, the wild type receptor, mutants E160Q and D170N, were not, suggesting that these acid residues participate in the modulatory mechanism. Poisson–Boltzmann analysis indicated that the E160Q and D170N mutants showed a shift towards more positive electrostatic potential in the SS2/SS3 microenvironment. Present results highlight the role of C132 and C149 as putative Zn(II) ligands; in addition, we infer that acid residues E160 and D170 play a role attracting Zn(II) to the head receptor domain.
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7
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Stokes L, Bidula S, Bibič L, Allum E. To Inhibit or Enhance? Is There a Benefit to Positive Allosteric Modulation of P2X Receptors? Front Pharmacol 2020; 11:627. [PMID: 32477120 PMCID: PMC7235284 DOI: 10.3389/fphar.2020.00627] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 04/21/2020] [Indexed: 12/15/2022] Open
Abstract
The family of ligand-gated ion channels known as P2X receptors were discovered several decades ago. Since the cloning of the seven P2X receptors (P2X1-P2X7), a huge research effort has elucidated their roles in regulating a range of physiological and pathophysiological processes. Transgenic animals have been influential in understanding which P2X receptors could be new therapeutic targets for disease. Furthermore, understanding how inherited mutations can increase susceptibility to disorders and diseases has advanced this knowledge base. There has been an emphasis on the discovery and development of pharmacological tools to help dissect the individual roles of P2X receptors and the pharmaceutical industry has been involved in pushing forward clinical development of several lead compounds. During the discovery phase, a number of positive allosteric modulators have been described for P2X receptors and these have been useful in assigning physiological roles to receptors. This review will consider the major physiological roles of P2X1-P2X7 and discuss whether enhancement of P2X receptor activity would offer any therapeutic benefit. We will review what is known about identified compounds acting as positive allosteric modulators and the recent identification of drug binding pockets for such modulators.
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Affiliation(s)
- Leanne Stokes
- School of Pharmacy, University of East Anglia, Norwich, United Kingdom
| | - Stefan Bidula
- School of Pharmacy, University of East Anglia, Norwich, United Kingdom
| | - Lučka Bibič
- School of Pharmacy, University of East Anglia, Norwich, United Kingdom
| | - Elizabeth Allum
- School of Pharmacy, University of East Anglia, Norwich, United Kingdom
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8
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Soto P, Gaete PS, Fuentes C, Lozano B, Naulin PA, Figueroa XF, Barrera NP. Function of P2X4 Receptors Is Directly Modulated by a 1:1 Stoichiometric Interaction With 5-HT 3A Receptors. Front Cell Neurosci 2020; 14:106. [PMID: 32431598 PMCID: PMC7214622 DOI: 10.3389/fncel.2020.00106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 04/07/2020] [Indexed: 12/30/2022] Open
Abstract
Interacting receptors at the neuronal plasma membrane represent an additional regulatory mode for intracellular transduction pathways. P2X4 receptor triggers fast neurotransmission responses via a transient increase in intracellular Ca2+ levels. It has been proposed that the P2X4 receptor interacts with the 5-HT3A receptor in hippocampal neurons, but their binding stoichiometry and the role of P2X4 receptor activation by ATP on this crosstalking system remains unknown. Via pull-down assays, total internal reflection fluorescence (TIRF) microscopy measurements of the receptors colocalization and expression at the plasma membrane, and atomic force microscopy (AFM) imaging, we have demonstrated that P2X4/5-HT3A receptor complexes can interact with each other in a 1:1 stoichiometric manner that is preserved after ATP binding. Also, macromolecular docking followed by 100 ns molecular dynamics (MD) simulations suggested that the interaction energy of the P2X4 receptor with 5-HT3A receptor is similar at the holo and the apo state of the P2X4 receptor, and the interacting 5-HT3A receptor decreased the ATP binding energy of P2X4 receptor. Finally, the P2X4 receptor-dependent Ca2+ mobilization is inhibited by the 5-HT3A interacting receptor. Altogether, these findings provide novel molecular insights into the allosteric regulation of P2X4/5-HT3A receptor complex in lipid bilayers of living cells via stoichiometric association, rather than accumulation or unspecific clustering of complexes.
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Affiliation(s)
- Paola Soto
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pablo S Gaete
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Christian Fuentes
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Benjamin Lozano
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pamela A Naulin
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Xavier F Figueroa
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Nelson Patricio Barrera
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
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9
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Sivcev S, Slavikova B, Rupert M, Ivetic M, Nekardova M, Kudova E, Zemkova H. Synthetic testosterone derivatives modulate rat P2X2 and P2X4 receptor channel gating. J Neurochem 2019; 150:28-43. [PMID: 31069814 DOI: 10.1111/jnc.14718] [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] [Received: 11/06/2018] [Revised: 04/24/2019] [Accepted: 04/29/2019] [Indexed: 12/25/2022]
Abstract
P2X receptors (P2XRs) are ATP-gated cationic channels that are allosterically modulated by numerous compounds, including steroids and neurosteroids. These compounds may both inhibit and potentiate the activity of P2XRs, but sex steroids such as 17β-estradiol or progesterone are reported to be inactive. Here, we tested a hypothesis that testosterone, another sex hormone, modulates activity of P2XRs. We examined actions of native testosterone and a series of testosterone derivatives on the gating of recombinant P2X2R, P2X4R and P2X7R and native channels expressed in pituitary cells and hypothalamic neurons. The 17β-ester derivatives of testosterone rapidly and positively modulate the 1 µM ATP-evoked currents in P2X2R- and P2X4R-expressing cells, but not agonist-evoked currents in P2X7R-expressing cells. In general, most of the tested testosterone derivatives are more potent modulators than endogenous testosterone. The comparison of chemical structures and whole-cell recordings revealed that their interactions with P2XRs depend on the lipophilicity and length of the alkyl chain at position C-17. Pre-treatment with testosterone butyrate or valerate increases the sensitivity of P2X2R and P2X4R to ATP by several fold, reduces the rate of P2X4R desensitization, accelerates resensitization, and enhances ethidium uptake by P2X4R. Native channels are also potentiated by testosterone derivatives, while endogenously expressed GABA receptors type A are inhibited. The effect of ivermectin, a P2X4R-specific allosteric modulator, on deactivation is antagonized by testosterone derivatives in a concentration-dependent manner. Together, our results provide evidence for potentiation of particular subtypes of P2XRs by testosterone derivatives and suggest a potential role of ivermectin binding site for steroid-induced modulation. 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. The complete Open Science Disclosure form for this article can be found at the end of the article. 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)
- Sonja Sivcev
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.,Faculty of Science, Charles University, Prague, Czech Republic
| | - Barbora Slavikova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Marian Rupert
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.,1st Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Milorad Ivetic
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Michaela Nekardova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic.,Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Hana Zemkova
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
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10
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Ilyaskin AV, Sure F, Nesterov V, Haerteis S, Korbmacher C. Bile acids inhibit human purinergic receptor P2X4 in a heterologous expression system. J Gen Physiol 2019; 151:820-833. [PMID: 30988062 PMCID: PMC6572003 DOI: 10.1085/jgp.201812291] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 03/08/2019] [Accepted: 03/22/2019] [Indexed: 12/22/2022] Open
Abstract
We recently demonstrated that bile acids, especially tauro-deoxycholic acid (t-DCA), modify the function of the acid-sensing ion channel ASIC1a and other members of the epithelial sodium channel (ENaC)/degenerin (DEG) ion channel family. Surprisingly, ASIC1 shares a high degree of structural similarity with the purinergic receptor P2X4, a nonselective cation channel transiently activated by ATP. P2X4 is abundantly expressed in the apical membrane of bile duct epithelial cells and is therefore exposed to bile acids under physiological conditions. Here, we hypothesize that P2X4 may also be modulated by bile acids and investigate whether t-DCA and other common bile acids affect human P2X4 heterologously expressed in Xenopus laevis oocytes. We find that application of either t-DCA or unconjugated deoxycholic acid (DCA; 250 µM) causes a strong reduction (∼70%) of ATP-activated P2X4-mediated whole-cell currents. The inhibitory effect of 250 µM tauro-chenodeoxycholic acid is less pronounced (∼30%), and 250 µM chenodeoxycholic acid, cholic acid, or tauro-cholic acid did not significantly alter P2X4-mediated currents. t-DCA inhibits P2X4 in a concentration-dependent manner by reducing the efficacy of ATP without significantly changing its affinity. Single-channel patch-clamp recordings provide evidence that t-DCA inhibits P2X4 by stabilizing the channel's closed state. Using site-directed mutagenesis, we identifiy several amino acid residues within the transmembrane domains of P2X4 that are critically involved in mediating the inhibitory effect of t-DCA on P2X4. Importantly, a W46A mutation converts the inhibitory effect of t-DCA into a stimulatory effect. We conclude that t-DCA directly interacts with P2X4 and decreases ATP-activated P2X4 currents by stabilizing the closed conformation of the channel.
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Affiliation(s)
- Alexandr V Ilyaskin
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Florian Sure
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Silke Haerteis
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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11
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Pasqualetto G, Brancale A, Young MT. The Molecular Determinants of Small-Molecule Ligand Binding at P2X Receptors. Front Pharmacol 2018; 9:58. [PMID: 29456508 PMCID: PMC5801290 DOI: 10.3389/fphar.2018.00058] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 01/17/2018] [Indexed: 12/30/2022] Open
Abstract
P2X receptors are trimeric eukaryotic ATP-gated cation channels. Extracellular ATP—their physiological ligand—is released as a neurotransmitter and in conditions of cell damage such as inflammation, and substantial evidence implicates P2X receptors in diseases including neuropathic pain, cancer, and arthritis. In 2009, the first P2X crystal structure, Danio rerio P2X4 in the apo- state, was published, and this was followed in 2012 by the ATP-bound structure. These structures transformed our understanding of the conformational changes induced by ATP binding and the mechanism of ligand specificity, and enabled homology modeling of mammalian P2X receptors for ligand docking and rational design of receptor modulators. P2X receptors are attractive drug targets, and a wide array of potent, subtype-selective modulators (mostly antagonists) have been developed. In 2016, crystal structures of human P2X3 in complex with the competitive antagonists TNP-ATP and A-317491, and Ailuropoda melanoleuca P2X7 in complex with a series of allosteric antagonists were published, giving fascinating insights into the mechanism of channel antagonism. In this article we not only summarize current understanding of small-molecule modulator binding at P2X receptors, but also use this information in combination with previously published structure-function data and molecular docking experiments, to hypothesize a role for the dorsal fin loop region in differential ATP potency, and describe novel, testable binding conformations for both the semi-selective synthetic P2X7 agonist 2′-(3′)-O-(4-benzoyl)benzoyl ATP (BzATP), and the P2X4-selective positive allosteric modulator ivermectin. We find that the distal benzoyl group of BzATP lies in close proximity to Lys-127, a residue previously implicated in BzATP binding to P2X7, potentially explaining the increased potency of BzATP at rat P2X7 receptors. We also present molecular docking of ivermectin to rat P2X4 receptors, illustrating a plausible binding conformation between the first and second transmembrane domains which not only tallies with previous mutagenesis studies, but would also likely have the effect of stabilizing the open channel structure, consistent with the mode of action of this positive allosteric modulator. From our docking simulations and analysis of sequence homology we propose a series of mutations likely to confer ivermectin sensitivity to human P2X1.
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Affiliation(s)
- Gaia Pasqualetto
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom
| | - Andrea Brancale
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom
| | - Mark T Young
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
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