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Volpato D, Kauk M, Messerer R, Bermudez M, Wolber G, Bock A, Hoffmann C, Holzgrabe U. The Role of Orthosteric Building Blocks of Bitopic Ligands for Muscarinic M1 Receptors. ACS OMEGA 2020; 5:31706-31715. [PMID: 33344823 PMCID: PMC7745449 DOI: 10.1021/acsomega.0c04220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/16/2020] [Indexed: 05/13/2023]
Abstract
The muscarinic M1 acetylcholine receptor is an important drug target for the treatment of various neurological disorders. Designing M1 receptor-selective drugs has proven challenging, mainly due to the high conservation of the acetylcholine binding site among muscarinic receptor subtypes. Therefore, less conserved and topographically distinct allosteric binding sites have been explored to increase M1 receptor selectivity. In this line, bitopic ligands, which target orthosteric and allosteric binding sites simultaneously, may provide a promising strategy. Here, we explore the allosteric, M1-selective BQCAd scaffold derived from BQCA as a starting point for the design, synthesis, and pharmacological evaluation of a series of novel bitopic ligands in which the orthosteric moieties and linker lengths are systematically varied. Since β-arrestin recruitment seems to be favorable to therapeutic implication, all the compounds were investigated by G protein and β-arrestin assays. Some bitopic ligands are partial to full agonists for G protein activation, some activate β-arrestin recruitment, and the degree of β-arrestin recruitment varies according to the respective modification. The allosteric BQCAd scaffold controls the positioning of the orthosteric ammonium group of all ligands, suggesting that this interaction is essential for stimulating G protein activation. However, β-arrestin recruitment is not affected. The novel set of bitopic ligands may constitute a toolbox to study the requirements of β-arrestin recruitment during ligand design for therapeutic usage.
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Affiliation(s)
- Daniela Volpato
- Department
of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Michael Kauk
- Institute
for Molecular Cell Biology, CMB-Center for Molecular Biomedicine,
University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Regina Messerer
- Department
of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Marcel Bermudez
- Institute
of Pharmacy, Freie Universitaet Berlin, Königin-Luise-Str. 2-4 in 14195 Berlin-Dahlem, Germany
| | - Gerhard Wolber
- Institute
of Pharmacy, Freie Universitaet Berlin, Königin-Luise-Str. 2-4 in 14195 Berlin-Dahlem, Germany
| | - Andreas Bock
- Max
Delbrück Center for Molecular Medicine, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Carsten Hoffmann
- Institute
for Molecular Cell Biology, CMB-Center for Molecular Biomedicine,
University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Ulrike Holzgrabe
- Department
of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
- . Tel.: +49 931 31-85460
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Salazar-Fajardo PD, Aréchiga-Figueroa IA, López-Serrano AL, Rodriguez-Elias JC, Alamilla J, Sánchez-Chapula JA, Tristani-Firouzi M, Navarro-Polanco RA, Moreno-Galindo EG. The voltage-sensitive cardiac M 2 muscarinic receptor modulates the inward rectification of the G protein-coupled, ACh-gated K + current. Pflugers Arch 2018; 470:1765-1776. [PMID: 30155776 DOI: 10.1007/s00424-018-2196-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 07/28/2018] [Accepted: 08/13/2018] [Indexed: 11/25/2022]
Abstract
The acetylcholine (ACh)-gated inwardly rectifying K+ current (IKACh) plays a vital role in cardiac excitability by regulating heart rate variability and vulnerability to atrial arrhythmias. These crucial physiological contributions are determined principally by the inwardly rectifying nature of IKACh. Here, we investigated the relative contribution of two distinct mechanisms of IKACh inward rectification measured in atrial myocytes: a rapid component due to KACh channel block by intracellular Mg2+ and polyamines; and a time- and concentration-dependent mechanism. The time- and ACh concentration-dependent inward rectification component was eliminated when IKACh was activated by GTPγS, a compound that bypasses the muscarinic-2 receptor (M2R) and directly stimulates trimeric G proteins to open KACh channels. Moreover, the time-dependent component of IKACh inward rectification was also eliminated at ACh concentrations that saturate the receptor. These observations indicate that the time- and concentration-dependent rectification mechanism is an intrinsic property of the receptor, M2R; consistent with our previous work demonstrating that voltage-dependent conformational changes in the M2R alter the receptor affinity for ACh. Our analysis of the initial and time-dependent components of IKACh indicate that rapid Mg2+-polyamine block accounts for 60-70% of inward rectification, with M2R voltage sensitivity contributing 30-40% at sub-saturating ACh concentrations. Thus, while both inward rectification mechanisms are extrinsic to the KACh channel, to our knowledge, this is the first description of extrinsic inward rectification of ionic current attributable to an intrinsic voltage-sensitive property of a G protein-coupled receptor.
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Affiliation(s)
- Pedro D Salazar-Fajardo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico
| | - Iván A Aréchiga-Figueroa
- CONACyT, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, Mexico
| | - Ana Laura López-Serrano
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico
| | - Julio C Rodriguez-Elias
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico
| | - Javier Alamilla
- CONACyT, Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, COL, Mexico
| | - José A Sánchez-Chapula
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico
| | - Martin Tristani-Firouzi
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Ricardo A Navarro-Polanco
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico.
| | - Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico.
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Sturzbecher-Höhne M, Kissner R, Nauser T, Koppenol WH. Preparation and Properties of Lithium and Sodium Peroxynitrite. Chem Res Toxicol 2008; 21:2257-9. [DOI: 10.1021/tx800279n] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Manuel Sturzbecher-Höhne
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zürich, Switzerland
| | - Reinhard Kissner
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zürich, Switzerland
| | - Thomas Nauser
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zürich, Switzerland
| | - Willem H. Koppenol
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zürich, Switzerland
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4
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Wang Z, Shi H, Wang H. Functional M3 muscarinic acetylcholine receptors in mammalian hearts. Br J Pharmacol 2004; 142:395-408. [PMID: 15148264 PMCID: PMC1574958 DOI: 10.1038/sj.bjp.0705787] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2004] [Revised: 03/08/2004] [Accepted: 03/10/2004] [Indexed: 11/08/2022] Open
Abstract
In contrast to most peripheral tissues where multiple subtypes of muscarinic acetylcholine receptor (mAChR) coexist, with each of them playing its part in the orchestra of parasympathetic innervation, the myocardium has been traditionally considered to possess a single mAChR subtype. Although there is much evidence to support the notion that one receptor subtype (M2) orchestrates myocardial muscarinic transduction, there is emerging evidence that M1 and M3 receptors are also expressed and are of potential physiological, pathophysiological and pharmacological relevance. Clarifying this issue has a profound impact on our thinking about the cholinergic control of the heart function and disease and approaches to new drug development for the treatment of heart disease associated with parasympathetic dysfunction. This review article presents evidence for the presence of the M3 receptor subtype in the heart, and analyzes the controversial data from published pharmacological, functional and molecular studies. The potential roles of the M3 receptors, in parasympathetic control of heart function under normal physiological conditions and in heart failure, myocardial ischemia and arrhythmias, are discussed. On the basis of these considerations, we have made some proposals concerning the future of myocardial M3 receptor research.
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Affiliation(s)
- Zhiguo Wang
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, Quebec, Canada.
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Abstract
Anion transport proteins in mammalian cells participate in a wide variety of cell and intracellular organelle functions, including regulation of electrical activity, pH, volume, and the transport of osmolites and metabolites, and may even play a role in the control of immunological responses, cell migration, cell proliferation, and differentiation. Although significant progress over the past decade has been achieved in understanding electrogenic and electroneutral anion transport proteins in sarcolemmal and intracellular membranes, information on the molecular nature and physiological significance of many of these proteins, especially in the heart, is incomplete. Functional and molecular studies presently suggest that four primary types of sarcolemmal anion channels are expressed in cardiac cells: channels regulated by protein kinase A (PKA), protein kinase C, and purinergic receptors (I(Cl.PKA)); channels regulated by changes in cell volume (I(Cl.vol)); channels activated by intracellular Ca(2+) (I(Cl.Ca)); and inwardly rectifying anion channels (I(Cl.ir)). In most animal species, I(Cl.PKA) is due to expression of a cardiac isoform of the epithelial cystic fibrosis transmembrane conductance regulator Cl(-) channel. New molecular candidates responsible for I(Cl.vol), I(Cl.Ca), and I(Cl.ir) (ClC-3, CLCA1, and ClC-2, respectively) have recently been identified and are presently being evaluated. Two isoforms of the band 3 anion exchange protein, originally characterized in erythrocytes, are responsible for Cl(-)/HCO(3)(-) exchange, and at least two members of a large vertebrate family of electroneutral cotransporters (ENCC1 and ENCC3) are responsible for Na(+)-dependent Cl(-) cotransport in heart. A 223-amino acid protein in the outer mitochondrial membrane of most eukaryotic cells comprises a voltage-dependent anion channel. The molecular entities responsible for other types of electroneutral anion exchange or Cl(-) conductances in intracellular membranes of the sarcoplasmic reticulum or nucleus are unknown. Evidence of cardiac expression of up to five additional members of the ClC gene family suggest a rich new variety of molecular candidates that may underlie existing or novel Cl(-) channel subtypes in sarcolemmal and intracellular membranes. The application of modern molecular biological and genetic approaches to the study of anion transport proteins during the next decade holds exciting promise for eventually revealing the actual physiological, pathophysiological, and clinical significance of these unique transport processes in cardiac and other mammalian cells.
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Affiliation(s)
- J R Hume
- Department of Physiology, University of Nevada School of Medicine, Reno, Nevada, USA.
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Shi H, Wang H, Wang Z. M3 muscarinic receptor activation of a delayed rectifier potassium current in canine atrial myocytes. Life Sci 1999; 64:PL251-7. [PMID: 10353596 DOI: 10.1016/s0024-3205(99)00142-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Growing body of evidence indicates that the functional responses of cells to muscarinic acetylcholine receptors (mAChRs) are mediated by multiple receptor subtypes. It is commonly thought that the M2 receptor is the only functional mAChR subtype in the heart and little data regarding the potential roles of other subtypes in cardiac tissues has been reported. In the present study, we provide functional evidence for the presence and physiological function of an M3 receptor in canine atrial myocytes. Using whole-cell patch-clamp techniques, we consistently found that pilocarpine, an mAChR agonist, induced a K+ current similar to but distinct from the classical delayed rectifier K+ current. Same observations were obtained when choline or tetramethylammonium (TMA) was applied to the bath. The currents were abolished by 1 microM atropine. Antagonists selective to M1 (pirenzepine, 100 nM), M2 (methoctramine 100 nM), or M4 (tropicamide 200 nM) receptors failed to alter the currents. Conversely, three different M3-selective inhibitors, p-F-HHSiD (20-200 nM), 4-DAMP methiodide (2-10 nM) and 4-DAMP mustard (4-20 nM), all produced concentration-dependent suppression of the currents. A cDNA fragment representing the M3 receptor was isolated from dog atrial RNA and the mRNA level of this construct was 0.7 +/- 0.1 pg/microg total RNA, as quantified by the competitive RT-PCR methods. Our data strongly suggested that an M3 receptor exists and is coupled to a K+ channel in the heart.
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Affiliation(s)
- H Shi
- Research Center, Montreal Heart Institute, Quebec, Canada
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Yan GX, Chen J, Yamada KA, Kléber AG, Corr PB. Contribution of shrinkage of extracellular space to extracellular K+ accumulation in myocardial ischaemia of the rabbit. J Physiol 1996; 490 ( Pt 1):215-28. [PMID: 8745289 PMCID: PMC1158658 DOI: 10.1113/jphysiol.1996.sp021137] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
1. The contribution of the concentrating effect due to shrinkage of the extracellular space (ECS) to cellular K+ efflux on extracellular potassium ([K+]o) accumulation in response to ischaemia was investigated in an isolated, blood-perfused rabbit papillary muscle preparation with a confined extracellular space. 2. The ECS was quantified using either of two extracellular markers, choline or tetramethyl ammonium (TMA), each with specific ion-selective electrodes, as well as by measurement of extracellular resistance (ro). [K+]o and [Na+]o were also measured simultaneously using K(+)- and Na(+)-selective electrodes. 3. During ischaemia, [K+]o increased 3-fold from 4.2 +/- 0.1 to 12.6 +/- 1.0 mM at 10 min (n = 10) analogous to changes in the ischaemic heart in vivo. The ECS decreased to 83.9 +/- 3.2% of control measured using 1 mM choline extracellularly (n = 9, P < 0.01) or to 85.7 +/- 0.7% of control using 1 mM TMA (n = 6, P < 0.01). Nearly identical decreases in ro (84.1 +/- 2.4%, n = 15, P < 0.01) occurred simultaneously. 4. The small decrease in the ECS contributed only 0.8-0.9 mM to the total increase in [K+]o of 8.4 mM and had a minor effect on transmembrane K+ flux. No significant differences between the relative changes in [choline] and [Na+]o were observed. This excluded a major transmembrane Na+ movement during early ischaemia. 5. Bumetanide (10 mM), an inhibitor of K(+)-Cl- cotransport, a process which is involved in cell volume regulation consequent to osmotic cell swelling, significantly attenuated the increase in [K+]o after 6 min of ischaemia (8.3 +/- 0.6 mM, n = 5 vs. 10.3 +/- 0.4 mM in the control group, n = 6, P < 0.05), whereas N-ethylmaleimide (1 mM), a stimulator of this cotransporter, augmented [K+]o accumulation (12.0 +/- 0.6 mM at 6 min, P < 0.05). 6. We conclude that during early myocardial ischaemia, a major component of [K+]o accumulation is not caused by diminution of ECS per se, but rather by increased net K+ efflux due in part to K(+)-Cl cotransport secondary to myocyte volume regulation.
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Affiliation(s)
- G X Yan
- Department of Internal Medicine, Washington University School of Medicine, St Louis, MO, USA
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