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Azargoonjahromi A. Current Findings and Potential Mechanisms of KarXT (Xanomeline-Trospium) in Schizophrenia Treatment. Clin Drug Investig 2024; 44:471-493. [PMID: 38904739 DOI: 10.1007/s40261-024-01377-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2024] [Indexed: 06/22/2024]
Abstract
Standard schizophrenia treatment involves antipsychotic medications that target D2 dopamine receptors. However, these drugs have limitations in addressing all symptoms and can lead to adverse effects such as motor impairments, metabolic effects, sedation, sexual dysfunction, cognitive impairment, and tardive dyskinesia. Recently, KarXT has emerged as a novel drug for schizophrenia. KarXT combines xanomeline, a muscarinic receptor M1 and M4 agonist, with trospium, a nonselective antimuscarinic agent. Of note, xanomeline can readily cross blood-brain barrier (BBB) and, thus, enter into the brain, thereby stimulating muscarinic receptors (M1 and M4). By doing so, xanomeline has been shown to target negative symptoms and potentially improve positive symptoms. Trospium, on the other hand, is not able to cross BBB, thereby not affecting M1 and M4 receptors; instead, it acts as an antimuscarinic agent and, hence, diminishes peripheral activity of muscarinic receptors to minimize side effects probably stemming from xanomeline in other organs. Accordingly, ongoing clinical trials investigating KarXT's efficacy in schizophrenia have demonstrated positive outcomes, including significant improvements in the Positive and Negative Syndrome Scale (PANSS) total score and cognitive function compared with placebo. These findings emphasize the potential of KarXT as a promising treatment for schizophrenia, providing symptom relief while minimizing side effects associated with xanomeline monotherapy. Despite such promising evidence, further research is needed to confirm the efficacy, safety, and tolerability of KarXT in managing schizophrenia. This review article explores the current findings and potential mechanisms of KarXT in the treatment of schizophrenia.
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Affiliation(s)
- Ali Azargoonjahromi
- Shiraz University of Medical Sciences, Janbazan Blv, 14th Alley, Jahrom, Shiraz, 7417773539, Fars, Iran.
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2
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Nelic D, Chetverikov N, Hochmalová M, Diaz C, Doležal V, Boulos J, Jakubík J, Martemyanov K, Janoušková-Randáková A. Agonist-selective activation of individual G-proteins by muscarinic receptors. Sci Rep 2024; 14:9652. [PMID: 38671143 PMCID: PMC11053168 DOI: 10.1038/s41598-024-60259-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 04/20/2024] [Indexed: 04/28/2024] Open
Abstract
Selective activation of individual subtypes of muscarinic receptors is a promising way to safely alleviate a wide range of pathological conditions in the central nervous system and the periphery as well. The flexible G-protein interface of muscarinic receptors allows them to interact with several G-proteins with various efficacy, potency, and kinetics. Agonists biased to the particular G-protein mediated pathway may result in selectivity among muscarinic subtypes and, due to the non-uniform expression of individual G-protein alpha subunits, possibly achieve tissue specificity. Here, we demonstrate that novel tetrahydropyridine-based agonists exert specific signalling profiles in coupling with individual G-protein α subunits. These signalling profiles profoundly differ from the reference agonist carbachol. Moreover, coupling with individual Gα induced by these novel agonists varies among subtypes of muscarinic receptors which may lead to subtype selectivity. Thus, the novel tetrahydropyridine-based agonist can contribute to the elucidation of the mechanism of pathway-specific activation of muscarinic receptors and serve as a starting point for the development of desired selective muscarinic agonists.
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Affiliation(s)
- Dominik Nelic
- Department of Neurochemistry, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Nikolai Chetverikov
- Department of Neurochemistry, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Martina Hochmalová
- Department of Neurochemistry, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Christina Diaz
- Department of Physical Sciences, Barry University, Miami Shores, Miami, FL, USA
| | - Vladimír Doležal
- Department of Neurochemistry, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - John Boulos
- Department of Physical Sciences, Barry University, Miami Shores, Miami, FL, USA
| | - Jan Jakubík
- Department of Neurochemistry, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Kirill Martemyanov
- Department of Neuroscience, UF Scripps Biomedical Research, University of Florida, Jupiter, FL, 33458, USA.
| | - Alena Janoušková-Randáková
- Department of Neurochemistry, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
- Department of Neuroscience, UF Scripps Biomedical Research, University of Florida, Jupiter, FL, 33458, USA.
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3
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Powers AS, Pham V, Burger WAC, Thompson G, Laloudakis Y, Barnes NW, Sexton PM, Paul SM, Christopoulos A, Thal DM, Felder CC, Valant C, Dror RO. Structural basis of efficacy-driven ligand selectivity at GPCRs. Nat Chem Biol 2023; 19:805-814. [PMID: 36782010 PMCID: PMC10299909 DOI: 10.1038/s41589-022-01247-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 12/21/2022] [Indexed: 02/15/2023]
Abstract
A drug's selectivity for target receptors is essential to its therapeutic utility, but achieving selectivity between similar receptors is challenging. The serendipitous discovery of ligands that stimulate target receptors more strongly than closely related receptors, despite binding with similar affinities, suggests a solution. The molecular mechanism of such 'efficacy-driven selectivity' has remained unclear, however, hindering design of such ligands. Here, using atomic-level simulations, we reveal the structural basis for the efficacy-driven selectivity of a long-studied clinical drug candidate, xanomeline, between closely related muscarinic acetylcholine receptors (mAChRs). Xanomeline's binding mode is similar across mAChRs in their inactive states but differs between mAChRs in their active states, with divergent effects on active-state stability. We validate this mechanism experimentally and use it to design ligands with altered efficacy-driven selectivity. Our results suggest strategies for the rational design of ligands that achieve efficacy-driven selectivity for many pharmaceutically important G-protein-coupled receptors.
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Affiliation(s)
- Alexander S Powers
- Department of Chemistry, Stanford University, Stanford, CA, USA
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Vi Pham
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Wessel A C Burger
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Geoff Thompson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Yianni Laloudakis
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Nicholas W Barnes
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | | | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Neuromedicines Discovery Center, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - David M Thal
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | | | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia.
| | - Ron O Dror
- Department of Computer Science, Stanford University, Stanford, CA, USA.
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA.
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4
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Kidambi N, Elsayed OH, El-Mallakh RS. Xanomeline-Trospium and Muscarinic Involvement in Schizophrenia. Neuropsychiatr Dis Treat 2023; 19:1145-1151. [PMID: 37193547 PMCID: PMC10183173 DOI: 10.2147/ndt.s406371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 04/01/2023] [Indexed: 05/18/2023] Open
Abstract
Schizophrenia is a severe mental illness that has its onset in late adolescence or early adulthood and is associated with significant dysfunction across multiple domains. The pathogenesis of schizophrenia remains unknown, but physiologic understanding of the illness has been driven by the dopamine hypothesis. However, acetylcholine (ACh) clearly plays a role with mixed results regarding effect on psychosis. Selective muscarinic M1 and M4 agonists, such as xanomeline, originally developed to aid in cognitive loss with Alzheimer's, showed promise in proof-of-concept study in 20 patients with schizophrenia. Unfortunately, tolerability problems made muscarinic agonists impractical in either condition. However, coadministration of trospium, a lipophobic, non-selective muscarinic antagonist previously used for the treatment of overactive bladder, with xanomeline resulted in a significant reduction of cholinergic adverse effects. A recent randomized, placebo-controlled study of the antipsychotic effects of this combination in 182 patients with acute psychosis revealed improved tolerability with 80% of subjects staying to the end of the 5 weeks study. At the end of the trial, the treatment group saw a -17.4 change in the positive and negative symptom scale (PANSS) score from baseline compared to a -5.9 change in the placebo arm (P < 0.001). Furthermore, the negative symptom subscore, was also superior in the active arm (P < 0.001). These early studies are exciting because they suggest that the cholinergic system may be recruited to treat a severe and disabling disorder with suboptimal treatment options. Xanomeline-trospium combination is currently in phase III studies.
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Affiliation(s)
- Neil Kidambi
- Mood Disorders Research Program, Depression Center, Department of Psychiatry and Behavioral Sciences, University of Louisville School of Medicine, Louisville, KY, 40202, USA
| | - Omar H Elsayed
- Mood Disorders Research Program, Depression Center, Department of Psychiatry and Behavioral Sciences, University of Louisville School of Medicine, Louisville, KY, 40202, USA
| | - Rif S El-Mallakh
- Mood Disorders Research Program, Depression Center, Department of Psychiatry and Behavioral Sciences, University of Louisville School of Medicine, Louisville, KY, 40202, USA
- Correspondence: Rif S El-Mallakh, Mood Disorders Research Program, Depression Center, Department of Psychiatry and Behavioral Sciences, University of Louisville School of Medicine, Louisville, KY, 40202, USA, Tel +1 502 588 4450, Fax +1 502 588 9539, Email
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5
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Katayama K, Suzuki K, Suno R, Kise R, Tsujimoto H, Iwata S, Inoue A, Kobayashi T, Kandori H. Vibrational spectroscopy analysis of ligand efficacy in human M 2 muscarinic acetylcholine receptor (M 2R). Commun Biol 2021; 4:1321. [PMID: 34815515 PMCID: PMC8635417 DOI: 10.1038/s42003-021-02836-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 11/01/2021] [Indexed: 12/30/2022] Open
Abstract
The intrinsic efficacy of ligand binding to G protein-coupled receptors (GPCRs) reflects the ability of the ligand to differentially activate its receptor to cause a physiological effect. Here we use attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy to examine the ligand-dependent conformational changes in the human M2 muscarinic acetylcholine receptor (M2R). We show that different ligands affect conformational alteration appearing at the C=O stretch of amide-I band in M2R. Notably, ATR-FTIR signals strongly correlated with G-protein activation levels in cells. Together, we propose that amide-I band serves as an infrared probe to distinguish the ligand efficacy in M2R and paves the path to rationally design ligands with varied efficacy towards the target GPCR.
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Affiliation(s)
- Kota Katayama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
| | - Kohei Suzuki
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
| | - Ryoji Suno
- Department of Medical Chemistry, Kansai Medical University, Hirakata, 573-1010, Japan
| | - Ryoji Kise
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Hirokazu Tsujimoto
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - So Iwata
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Takuya Kobayashi
- Department of Medical Chemistry, Kansai Medical University, Hirakata, 573-1010, Japan
- Japan Agency for Medical Research and Development, Core Research for Evolutional Science and Technology (AMED-CREST), Chiyoda-ku, Tokyo, 100-0004, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
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6
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Fusion with Promiscuous Gα 16 Subunit Reveals Signaling Bias at Muscarinic Receptors. Int J Mol Sci 2021; 22:ijms221810089. [PMID: 34576254 PMCID: PMC8469978 DOI: 10.3390/ijms221810089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/06/2021] [Accepted: 09/14/2021] [Indexed: 11/25/2022] Open
Abstract
A complex evaluation of agonist bias at G-protein coupled receptors at the level of G-protein classes and isoforms including non-preferential ones is essential for advanced agonist screening and drug development. Molecular crosstalk in downstream signaling and a lack of sufficiently sensitive and selective methods to study direct coupling with G-protein of interest complicates this analysis. We performed binding and functional analysis of 11 structurally different agonists on prepared fusion proteins of individual subtypes of muscarinic receptors and non-canonical promiscuous α-subunit of G16 protein to study agonist bias. We have demonstrated that fusion of muscarinic receptors with Gα16 limits access of other competitive Gα subunits to the receptor, and thus enables us to study activation of Gα16 mediated pathway more specifically. Our data demonstrated agonist-specific activation of G16 pathway among individual subtypes of muscarinic receptors and revealed signaling bias of oxotremorine towards Gα16 pathway at the M2 receptor and at the same time impaired Gα16 signaling of iperoxo at M5 receptors. Our data have shown that fusion proteins of muscarinic receptors with α-subunit of G-proteins can serve as a suitable tool for studying agonist bias, especially at non-preferential pathways.
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7
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Randáková A, Jakubík J. Functionally selective and biased agonists of muscarinic receptors. Pharmacol Res 2021; 169:105641. [PMID: 33951507 DOI: 10.1016/j.phrs.2021.105641] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/21/2021] [Accepted: 04/22/2021] [Indexed: 12/24/2022]
Abstract
Disruption of cholinergic signalling via muscarinic receptors is associated with various pathologies, like Alzheimer's disease or schizophrenia. Selective muscarinic agonists possess therapeutic potential in the treatment of diabetes, pain or Sjögren's syndrome. The orthosteric binding site of all subtypes of the muscarinic receptor is structurally identical, making the development of affinity-based selective agonists virtually impossible. Some agonists, however, are functionally selective; they activate only a subset of receptors or signalling pathways. Others may stabilise specific conformations of the receptor leading to non-uniform modulation of individual signalling pathways (biased agonists). Functionally selective and biased agonists represent a promising approach for selective activation of individual subtypes of muscarinic receptors. In this work we review chemical structures, receptor binding and agonist-specific conformations of currently known functionally selective and biased muscarinic agonists in the context of their intricate intracellular signalling. Further, we take a perspective on the possible use of biased agonists for tissue and organ-specific activation of muscarinic receptors.
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Affiliation(s)
- Alena Randáková
- Institute of Physiology Czech Academy of Sciences, Prague, Czech Republic.
| | - Jan Jakubík
- Institute of Physiology Czech Academy of Sciences, Prague, Czech Republic.
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8
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Khajehali E, Bradley S, van der Westhuizen ET, Molloy C, Valant C, Finlayson L, Lindsley CW, Sexton PM, Tobin AB, Christopoulos A. Restoring Agonist Function at a Chemogenetically Modified M 1 Muscarinic Acetylcholine Receptor. ACS Chem Neurosci 2020; 11:4270-4279. [PMID: 33196174 PMCID: PMC7616161 DOI: 10.1021/acschemneuro.0c00540] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Designer receptors exclusively activated by designer drugs (DREADDs) have been successfully employed to activate signaling pathways associated with specific muscarinic acetylcholine receptor (mAChR) subtypes. The M1 DREADD mAChR displays minimal responsiveness to the endogenous agonist acetylcholine (ACh) but responds to clozapine-N-oxide (CNO), an otherwise pharmacologically inert ligand. We have previously shown that benzyl quinolone carboxylic acid (BQCA), an M1 mAChR positive allosteric modulator (PAM), can rescue ACh responsiveness at these receptors. However, whether this effect is chemotype specific or applies to next-generation M1 PAMs with distinct scaffolds is unknown. Here, we reveal that new M1 PAMs restore ACh function at the M1 DREADD while modulating ACh binding at the M1 wild-type mAChR. Importantly, we demonstrate that the modulation of ACh function by M1 PAMs is translated in vivo using transgenic M1 DREADD mice. Our data provide important insights into mechanisms that define allosteric ligand modulation of agonist affinity vs efficacy and how these effects play out in the regulation of in vivo responses.
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Affiliation(s)
- Elham Khajehali
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Sophie Bradley
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Emma T van der Westhuizen
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Colin Molloy
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Lisa Finlayson
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Craig W Lindsley
- Department of Chemistry, Department of Pharmacology, Vanderbilt Center for Neuroscience Drug Discovery, Nashville, Tennessee 37232, United States
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Andrew B Tobin
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
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9
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Randáková A, Nelic D, Doležal V, El-Fakahany EE, Boulos J, Jakubík J. Agonist-Specific Conformations of the M 2 Muscarinic Acetylcholine Receptor Assessed by Molecular Dynamics. J Chem Inf Model 2020; 60:2325-2338. [PMID: 32130001 DOI: 10.1021/acs.jcim.0c00041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Binding of muscarinic ligands, both antagonists and agonists, and their effects on the conformation of the M2 acetylcholine receptor were modeled in silico and compared to experimental data. After docking of antagonists to the M2 receptor in an inactive conformation (3UON, 5ZK3, 5ZKB, or 5ZKB) and agonists in an active conformation (4MQS), 100 ns of conventional molecular dynamics (MD) followed by 500 ns of accelerated MD was run. Conventional MD revealed ligand-specific interactions with the receptor. Antagonists stabilized the receptor in an inactive conformation during accelerated MD. The receptor in complex with various agonists attained different conformations specific to individual agonists. The magnitude of the TM6 movement correlated with agonist efficacy at the non-preferential Gs pathway. The shape of the intracellular opening where the receptor interacts with a G-protein was different for the classical agonist carbachol, super-agonist iperoxo, and Gi/o-biased partial agonists JR-6 and JR-7, being compatible with experimentally observed agonist bias at the G-protein level. Moreover, a wash-resistant binding of the unique agonist xanomeline associated with interactions with membrane lipids was formed during accelerated MD. Thus, accelerated MD is suitable for modeling of ligand-specific receptor binding and receptor conformations that is essential for the design of experiments aimed at identification of the secondary binding sites and understanding molecular mechanisms underlying receptor activation.
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Affiliation(s)
- Alena Randáková
- Department of Neurochemistry, Institute of Physiology CAS, Prague, CZ 142 20, Czech Republic
| | - Dominik Nelic
- Department of Neurochemistry, Institute of Physiology CAS, Prague, CZ 142 20, Czech Republic
| | - Vladimír Doležal
- Department of Neurochemistry, Institute of Physiology CAS, Prague, CZ 142 20, Czech Republic
| | - Esam E El-Fakahany
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, Minnesota 55455, United States
| | - John Boulos
- Department of Physical Sciences, Barry University, Miami Shores, Florida 33161, United States
| | - Jan Jakubík
- Department of Neurochemistry, Institute of Physiology CAS, Prague, CZ 142 20, Czech Republic
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10
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Jakubik J, El-Fakahany EE. Current Advances in Allosteric Modulation of Muscarinic Receptors. Biomolecules 2020; 10:biom10020325. [PMID: 32085536 PMCID: PMC7072599 DOI: 10.3390/biom10020325] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/14/2020] [Accepted: 02/16/2020] [Indexed: 02/07/2023] Open
Abstract
Allosteric modulators are ligands that bind to a site on the receptor that is spatially separated from the orthosteric binding site for the endogenous neurotransmitter. Allosteric modulators modulate the binding affinity, potency, and efficacy of orthosteric ligands. Muscarinic acetylcholine receptors are prototypical allosterically-modulated G-protein-coupled receptors. They are a potential therapeutic target for the treatment of psychiatric, neurologic, and internal diseases like schizophrenia, Alzheimer’s disease, Huntington disease, type 2 diabetes, or chronic pulmonary obstruction. Here, we reviewed the progress made during the last decade in our understanding of their mechanisms of binding, allosteric modulation, and in vivo actions in order to understand the translational impact of studying this important class of pharmacological agents. We overviewed newly developed allosteric modulators of muscarinic receptors as well as new spin-off ideas like bitopic ligands combining allosteric and orthosteric moieties and photo-switchable ligands based on bitopic agents.
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Affiliation(s)
- Jan Jakubik
- Department of Neurochemistry, Institute of Physiology CAS, 142 20 Prague, Czech Republic
- Correspondence: (J.J.); (E.E.E.-F.)
| | - Esam E. El-Fakahany
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, MN 55455, USA
- Correspondence: (J.J.); (E.E.E.-F.)
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11
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Randáková A, Nelic D, Ungerová D, Nwokoye P, Su Q, Doležal V, El-Fakahany EE, Boulos J, Jakubík J. Novel M 2 -selective, G i -biased agonists of muscarinic acetylcholine receptors. Br J Pharmacol 2020; 177:2073-2089. [PMID: 31910288 DOI: 10.1111/bph.14970] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE More than 30% of currently marketed medications act via GPCRs. Thus, GPCRs represent one of the most important pharmacotherapeutic targets. In contrast to traditional agonists activating multiple signalling pathways, agonists activating a single signalling pathway represent a new generation of drugs with increased specificity and fewer adverse effects. EXPERIMENTAL APPROACH We have synthesized novel agonists of muscarinic ACh receptors and tested their binding and function (on levels of cAMP and inositol phosphates) in CHO cells expressing individual subtypes of muscarinic receptors, primary cultures of rat aortic smooth muscle cells and suspensions of digested native tissues from rats. Binding of the novel compounds to M2 receptors was modelled in silico. KEY RESULTS Two of the tested new compounds (1-(thiophen-2-ylmethyl)-3,6-dihydro-2H-pyridinium and 1-methyl-1-(thiophen-2-ylmethyl)-3,6-dihydro-2H-pyridinium) only inhibited cAMP synthesis in CHO cells, primary cultures, and native tissues, with selectivity for M2 muscarinic receptors and displaying bias towards the Gi signalling pathway at all subtypes of muscarinic receptors. Molecular modelling revealed interactions with the orthosteric binding site in a way specific for a given agonist followed by agonist-specific changes in the conformation of the receptor. CONCLUSIONS AND IMPLICATIONS The identified compounds may serve as lead structures in the search for novel non-steroidal and non-opioid analgesics acting via M2 and M4 muscarinic receptors with reduced side effects associated with activation of the phospholipase C signalling pathway.
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Affiliation(s)
- Alena Randáková
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
| | - Dominik Nelic
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
| | - Dana Ungerová
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
| | - Peter Nwokoye
- Department of Physical Sciences, Barry University, Miami Shores, Florida
| | - Qiwen Su
- Department of Physical Sciences, Barry University, Miami Shores, Florida
| | - Vladimír Doležal
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
| | - Esam E El-Fakahany
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, Minnesota
| | - John Boulos
- Department of Physical Sciences, Barry University, Miami Shores, Florida
| | - Jan Jakubík
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
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12
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Designing Hybrids Targeting the Cholinergic System by Modulating the Muscarinic and Nicotinic Receptors: A Concept to Treat Alzheimer's Disease. Molecules 2018; 23:molecules23123230. [PMID: 30544533 PMCID: PMC6320942 DOI: 10.3390/molecules23123230] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 01/02/2023] Open
Abstract
The cholinergic hypothesis has been reported first being the cause of memory dysfunction in the Alzheimer's disease. Researchers around the globe have focused their attention on understanding the mechanisms of how this complicated system contributes to processes such as learning, memory, disorientation, linguistic problems, and behavioral issues in the indicated chronic neurodegenerative disease. The present review reports recent updates in hybrid molecule design as a strategy for selectively addressing multiple target proteins involved in Alzheimer's disease (AD) and the study of their therapeutic relevance. The rationale and the design of the bifunctional compounds will be discussed in order to understand their potential as tools to investigate the role of the cholinergic system in AD.
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Structural insights into the subtype-selective antagonist binding to the M 2 muscarinic receptor. Nat Chem Biol 2018; 14:1150-1158. [PMID: 30420692 PMCID: PMC6462224 DOI: 10.1038/s41589-018-0152-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 09/14/2018] [Indexed: 11/23/2022]
Abstract
Human muscarinic receptor, M2 is one of the five subtypes of muscarinic receptors belonging to the family of G protein-coupled receptors. Muscarinic receptors are targets for multiple neurodegenerative diseases. The challenge has been designing subtype selective ligands against one of the five muscarinic receptors. We report high resolution structures of a thermostabilized mutant M2 receptor bound to a subtype selective antagonist AF-DX 384 and a non-selective antagonist NMS. The thermostabilizing mutation S110R in M2 was predicted using a theoretical strategy previously developed in our group. Comparison of the crystal structures and pharmacological properties of the M2 receptor shows that the Arg in the S110R mutant mimics the stabilizing role of the sodium cation, that is known to allosterically stabilize inactive state(s) of class A GPCRs. Molecular Dynamics simulations reveal that tightening of the ligand-residue contacts in M2 receptor compared to M3 receptor leads to subtype selectivity of AF-DX 384.
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Boulos JF, Jakubik J, Boulos JM, Randakova A, Momirov J. Synthesis of novel and functionally selective non-competitive muscarinic antagonists as chemical probes. Chem Biol Drug Des 2017. [PMID: 28646631 DOI: 10.1111/cbdd.13059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Muscarinic receptors are known to play important biological roles and are drug targets for several human diseases. In a pilot study, novel muscarinic antagonists were synthesized and used as chemical probes to obtain additional information of the muscarinic pharmacophore. The design of these ligands made use of current orthosteric and allosteric models of drug-receptor interactions together with chemical motifs known to achieve muscarinic receptor selectivity. This approach has led to the discovery of several non-competitive muscarinic ligands that strongly bind at a secondary receptor site. These compounds were found to be non-competitive antagonists that completely abolished carbachol activation in functional assays. Several of these compounds antagonized functional response to carbachol with great potency at M1 and M4 than at the rest of receptor subtypes.
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Affiliation(s)
- John F Boulos
- Department of Physical Sciences, Barry University, Miami Shores, FL, USA
| | - Jan Jakubik
- Department of Neurochemistry, Institute of Physiology of the Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - John M Boulos
- Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, USA
| | - Alena Randakova
- Department of Neurochemistry, Institute of Physiology of the Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jelena Momirov
- Department of Physical Sciences, Barry University, Miami Shores, FL, USA
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Pegoli A, She X, Wifling D, Hübner H, Bernhardt G, Gmeiner P, Keller M. Radiolabeled Dibenzodiazepinone-Type Antagonists Give Evidence of Dualsteric Binding at the M2 Muscarinic Acetylcholine Receptor. J Med Chem 2017; 60:3314-3334. [PMID: 28388054 DOI: 10.1021/acs.jmedchem.6b01892] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Andrea Pegoli
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
| | - Xueke She
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
| | - David Wifling
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
| | - Harald Hübner
- Department
of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstrasse 19, D-91052 Erlangen, Germany
| | - Günther Bernhardt
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
| | - Peter Gmeiner
- Department
of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstrasse 19, D-91052 Erlangen, Germany
| | - Max Keller
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
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Michal P, El-Fakahany EE, Doležal V. Changes in Membrane Cholesterol Differentially Influence Preferential and Non-preferential Signaling of the M1 and M3 Muscarinic Acetylcholine Receptors. Neurochem Res 2015; 40:2068-77. [PMID: 24821386 PMCID: PMC4630253 DOI: 10.1007/s11064-014-1325-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/19/2014] [Accepted: 05/03/2014] [Indexed: 01/13/2023]
Abstract
We have found earlier that changes in membrane cholesterol content have distinct impact on signaling via the M1, M2, or M3 receptors expressed in CHO cells (CHO-M1 through CHO-M3). Now we investigated whether gradual changes in membrane cholesterol exerts differential effects on coupling of the M1 and M3 muscarinic receptors to preferential signaling pathways through Gq/11 and non-preferential Gs G-proteins signaling. Changes in membrane cholesterol resulted in only marginal alterations of antagonist and agonist affinity of the M1 and M3 receptors, and did not influence precoupling of either subtype. Changes in membrane cholesterol did not influence parameters of carbachol-stimulated GTP-γ(35)S binding in CHO-M1 membranes while reduction as well as augmentation of membrane cholesterol lowered the efficacy but increased the potency of carbachol in CHO-M3 membranes. Gradual increase or decrease in membrane cholesterol concentration dependently attenuated agonist-induced inositolphosphates release while only cholesterol depletion increased basal values in both cell lines. Similarly, membrane cholesterol manipulation modified basal and agonist-stimulated cAMP synthesis via Gs in the same way in both cell lines. These results demonstrate that changes in membrane cholesterol concentration differentially impact preferential and non-preferential M1 and M3 receptor signaling. They point to the activated G-protein/effector protein interaction as the main site of action in alterations of M1 receptor-mediated stimulation of second messenger pathways. On the other hand, modifications in agonist-stimulated GTP-γ(35)S binding in CHO-M3 membranes indicate that in this case changes in ligand-activated receptor/G-protein interaction may also play a role.
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Affiliation(s)
- Pavel Michal
- Institute of Physiology, Academy of Sciences of the Czech Republic, v.v.i., Vídeňská 1083, 14220, Prague, Czech Republic
| | - Esam E El-Fakahany
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, MN, 55455, USA
| | - Vladimír Doležal
- Institute of Physiology, Academy of Sciences of the Czech Republic, v.v.i., Vídeňská 1083, 14220, Prague, Czech Republic.
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Lyukmanova EN, Shenkarev ZO, Shulepko MA, Paramonov AS, Chugunov AO, Janickova H, Dolejsi E, Dolezal V, Utkin YN, Tsetlin VI, Arseniev AS, Efremov RG, Dolgikh DA, Kirpichnikov MP. Structural Insight into Specificity of Interactions between Nonconventional Three-finger Weak Toxin from Naja kaouthia (WTX) and Muscarinic Acetylcholine Receptors. J Biol Chem 2015; 290:23616-30. [PMID: 26242733 PMCID: PMC4583006 DOI: 10.1074/jbc.m115.656595] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 07/29/2015] [Indexed: 11/06/2022] Open
Abstract
Weak toxin from Naja kaouthia (WTX) belongs to the group of nonconventional "three-finger" snake neurotoxins. It irreversibly inhibits nicotinic acetylcholine receptors and allosterically interacts with muscarinic acetylcholine receptors (mAChRs). Using site-directed mutagenesis, NMR spectroscopy, and computer modeling, we investigated the recombinant mutant WTX analogue (rWTX) which, compared with the native toxin, has an additional N-terminal methionine residue. In comparison with the wild-type toxin, rWTX demonstrated an altered pharmacological profile, decreased binding of orthosteric antagonist N-methylscopolamine to human M1- and M2-mAChRs, and increased antagonist binding to M3-mAChR. Positively charged arginine residues located in the flexible loop II were found to be crucial for rWTX interactions with all types of mAChR. Computer modeling suggested that the rWTX loop II protrudes to the M1-mAChR allosteric ligand-binding site blocking the entrance to the orthosteric site. In contrast, toxin interacts with M3-mAChR by loop II without penetration into the allosteric site. Data obtained provide new structural insight into the target-specific allosteric regulation of mAChRs by "three-finger" snake neurotoxins.
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Affiliation(s)
- Ekaterina N Lyukmanova
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia, the Lomonosov Moscow State University, 119991 Moscow, Russia,
| | - Zakhar O Shenkarev
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia, the Lomonosov Moscow State University, 119991 Moscow, Russia, the Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russian
| | - Mikhail A Shulepko
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia, the Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Alexander S Paramonov
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia, the Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Anton O Chugunov
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia, the Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Helena Janickova
- the Institute of Physiology, Academy of Sciences of the Czech Republic (Public Research Institution), 14220 Prague, Czech Republic, and
| | - Eva Dolejsi
- the Institute of Physiology, Academy of Sciences of the Czech Republic (Public Research Institution), 14220 Prague, Czech Republic, and
| | - Vladimir Dolezal
- the Institute of Physiology, Academy of Sciences of the Czech Republic (Public Research Institution), 14220 Prague, Czech Republic, and
| | - Yuri N Utkin
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Victor I Tsetlin
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Alexander S Arseniev
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia, the Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russian
| | - Roman G Efremov
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia, the Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russian
| | - Dmitry A Dolgikh
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia, the Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Mikhail P Kirpichnikov
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia, the Lomonosov Moscow State University, 119991 Moscow, Russia
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Riddy DM, Valant C, Rueda P, Charman WN, Sexton PM, Summers RJ, Christopoulos A, Langmead CJ. Label-Free Kinetics: Exploiting Functional Hemi-Equilibrium to Derive Rate Constants for Muscarinic Receptor Antagonists. Mol Pharmacol 2015; 88:779-90. [DOI: 10.1124/mol.115.100545] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 08/03/2015] [Indexed: 01/14/2023] Open
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19
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Randáková A, Dolejší E, Rudajev V, Zimčík P, Doležal V, El-Fakahany EE, Jakubík J. Classical and atypical agonists activate M1 muscarinic acetylcholine receptors through common mechanisms. Pharmacol Res 2015; 97:27-39. [DOI: 10.1016/j.phrs.2015.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/03/2015] [Accepted: 04/03/2015] [Indexed: 01/24/2023]
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20
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Šantrůčková E, Doležal V, El-Fakahany EE, Jakubík J. Long-term activation upon brief exposure to xanomleline is unique to M1 and M4 subtypes of muscarinic acetylcholine receptors. PLoS One 2014; 9:e88910. [PMID: 24558448 PMCID: PMC3928307 DOI: 10.1371/journal.pone.0088910] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 01/14/2014] [Indexed: 11/19/2022] Open
Abstract
Xanomeline is an agonist endowed with functional preference for M1/M4 muscarinic acetylcholine receptors. It also exhibits both reversible and wash-resistant binding to and activation of these receptors. So far the mechanisms of xanomeline selectivity remain unknown. To address this question we employed microfluorometric measurements of intracellular calcium levels and radioligand binding to investigate differences in the short- and long-term effects of xanomeline among muscarinic receptors expressed individually in Chinese hamster ovary cells. 1/One-min exposure of cells to xanomeline markedly increased intracellular calcium at hM1 and hM4, and to a lesser extent at hM2 and hM3 muscarinic receptors for more than 1 hour. 2/Unlike the classic agonists carbachol, oxotremorine, and pilocarpine 10-min exposure to xanomeline did not cause internalization of any receptor subtype. 3/Wash-resistant xanomeline selectively prevented further increase in intracellular calcium by carbachol at hM1 and hM4 receptors. 4/After transient activation xanomeline behaved as a long-term antagonist at hM5 receptors. 5/The antagonist N-methylscopolamine (NMS) reversibly blocked activation of hM1 through hM4 receptors by xanomeline. 6/NMS prevented formation of xanomeline wash-resistant binding and activation at hM2 and hM4 receptors and slowed them at hM1, hM3 and hM5 receptors. Our results show commonalities of xanomeline reversible and wash-resistant binding and short-time activation among the five muscarinic receptor subtypes. However long-term receptor activation takes place in full only at hM1 and hM4 receptors. Moreover xanomeline displays higher efficacy at hM1 and hM4 receptors in primary phasic intracellular calcium release. These findings suggest the existence of particular activation mechanisms specific to these two receptors.
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Affiliation(s)
- Eva Šantrůčková
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, United States of America
| | - Vladimír Doležal
- Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Esam E El-Fakahany
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, United States of America
| | - Jan Jakubík
- Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
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21
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JAKUBÍK J, ŠANTRŮČKOVÁ E, RANDÁKOVÁ A, JANÍČKOVÁ H, ZIMČÍK P, RUDAJEV V, MICHAL P, EL-FAKAHANY EE, DOLEŽAL V. Outline of Therapeutic Interventions With Muscarinic Receptor-Mediated Transmission. Physiol Res 2014; 63:S177-89. [DOI: 10.33549/physiolres.932675] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Muscarinc receptor-mediated signaling takes part in many physiological functions ranging from complex higher nervous activity to vegetative responses. Specificity of action of the natural muscarinic agonist acetylcholine is effected by action on five muscarinic receptor subtypes with particular tissue and cellular localization, and coupling preference with different G-proteins and their signaling pathways. In addition to physiological roles it is also implicated in pathologic events like promotion of carcinoma cells growth, early pathogenesis of neurodegenerative diseases in the central nervous system like Alzheimer´s disease and Parkinson´s disease, schizophrenia, intoxications resulting in drug addiction, or overactive bladder in the periphery. All of these disturbances demonstrate involvement of specific muscarinic receptor subtypes and point to the importance to develop selective pharmacotherapeutic interventions. Because of the high homology of the orthosteric binding site of muscarinic receptor subtypes there is virtually no subtype selective agonist that binds to this site. Activation of specific receptor subtypes may be achieved by developing allosteric modulators of acetylcholine binding, since ectopic binding domains on the receptor are less conserved compared to the orthosteric site. Potentiation of the effects of acetylcholine by allosteric modulators would be beneficial in cases where acetylcholine release is reduced due to pathological conditions. When presynaptic function is severly compromised, the utilization of ectopic agonists can be a thinkable solution.
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Affiliation(s)
| | | | | | | | | | | | | | | | - V. DOLEŽAL
- Department of Neurochemistry, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: G protein-coupled receptors. Br J Pharmacol 2013; 170:1459-581. [PMID: 24517644 PMCID: PMC3892287 DOI: 10.1111/bph.12445] [Citation(s) in RCA: 505] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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Kim SO, Dozier BL, Kerry JA, Duffy DM. EP3 receptor isoforms are differentially expressed in subpopulations of primate granulosa cells and couple to unique G-proteins. Reproduction 2013; 146:625-35. [PMID: 24062570 DOI: 10.1530/rep-13-0274] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Prostaglandin E2 (PGE2) produced within the ovarian follicle is necessary for ovulation. PGE2 is recognized by four distinct G-protein-coupled receptors. Among them, PTGER3 (also known as EP3) is unique in that mRNA splicing generates multiple isoforms. Each isoform has a distinct amino acid composition in the C-terminal region, which is involved in G-protein coupling. To determine whether monkey EP3 isoforms couple to different G-proteins, each EP3 isoform was expressed in Chinese hamster ovary cells, and intracellular signals were examined after stimulation with the EP3 agonist sulprostone. Stimulation of EP3 isoform 5 (EP3-5) reduced cAMP in a pertussis toxin (PTX)-sensitive manner, indicating involvement of Gαi. Stimulation of EP3-9 increased cAMP, which was reduced by the general G-protein inhibitor GDP-β-S, and also increased intracellular calcium, which was reduced by PTX and GDP-β-S. So, EP3-9 likely couples to both Gαs and a PTX-sensitive G-protein to regulate intracellular signals. Stimulation of EP3-14 increased cAMP, which was further increased by PTX, so EP3-14 likely regulates cAMP via multiple G-proteins. Granulosa cell expression of all EP3 isoforms increased in response to an ovulatory dose of human chorionic gonadotropin. Two EP3 isoforms were differentially expressed in functional subpopulations of granulosa cells. EP3-5 was low in granulosa cells at the follicle apex while EP3-9 was high in cumulus granulosa cells. Differential expression of EP3 isoforms may yield different intracellular responses to PGE2 in granulosa cell subpopulations, contributing to the different roles played by granulosa cell subpopulations in the process of ovulation.
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Boulos J, Jakubik J, Randakova A, Avila C. Synthesis ofN-Substituted Piperidine Salts as Potential Muscarinic Ligands for Alzheimer's Applications. J Heterocycl Chem 2013. [DOI: 10.1002/jhet.1742] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- John Boulos
- Department of Physical Sciences; Barry University; Miami Shores Florida 33161 USA
| | - Jan Jakubik
- Department of Neurochemistry; Institute of Physiology of the Academy of Sciences of the Czech Republic; v.v.i., 142 20 Prague Czech Republic
| | - Alena Randakova
- Department of Neurochemistry; Institute of Physiology of the Academy of Sciences of the Czech Republic; v.v.i., 142 20 Prague Czech Republic
| | - Cristina Avila
- Department of Physical Sciences; Barry University; Miami Shores Florida 33161 USA
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Abstract
The overproduction of β-amyloid (Aβ) fragments in transgenic APPswe/PS1dE9 mice results in formation of amyloid deposits in the cerebral cortex and hippocampus starting around four months of age and leading to cognitive impairment much later. We have previously found an age and transgene-dependent weakening of muscarinic receptor-mediated transmission that was not present in young (6-10-week-old) animals but preceded both amyloid deposits and cognitive deficits. Now we investigated immediate and prolonged in vitro effects of non-aggregated Aβ(1-42) on coupling of individual muscarinic receptor subtypes expressed in CHO (Chinese hamster ovary) cells and their underlying mechanisms. Immediate application of 1 μM Aβ(1-42) had no effect on the binding of the muscarinic antagonist N-methylscopolamine or the agonist carbachol. In contrast, 4-day treatment of CHO cells expressing the M1 muscarinic receptor with 100 nM Aβ(1-42) significantly changed the binding characteristics of the muscarinic agonist carbachol and reduced the extent of the M1 receptor-stimulated breakdown of phosphatidylinositol while it did not demonstrate overt toxic effects. The treatment had no influence on the expression of either G-proteins or muscarinic receptors. In concert, we found no change in the gene expression of muscarinic receptor subtypes and gene or protein expression of the G(s), G(q/11), and G(i/o) G-proteins in the cerebral cortex of young adult APPswe/PS1dE9 mice that demonstrate high concentrations of soluble Aβ(1-42) and impaired muscarinic receptor-mediated G-protein activation. Our results provide strong evidence that the initial injurious effects of Aβ(1-42) on M1 muscarinic receptor-mediated transmissionis is due to compromised coupling of the receptor with G(q/11) G-protein.
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Kucerova L, Broz V, Fleischmannova J, Santruckova E, Sidorov R, Dolezal V, Zurovec M. Characterization of the Drosophila adenosine receptor: the effect of adenosine analogs on cAMP signaling in Drosophila cells and their utility for in vivo experiments. J Neurochem 2012; 121:383-95. [PMID: 22353178 DOI: 10.1111/j.1471-4159.2012.07701.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Adenosine receptors (AR) belonging to the G protein-coupled receptor family influence a wide range of physiological processes. Recent elucidation of the structure of human A2AR revealed the conserved amino acids necessary for contact with the Ado moiety. However, the selectivity of Ado analogs for AR subtypes is still not well understood. We have shown previously that the Drosophila adenosine receptor (DmAdoR) evokes an increase in cAMP and calcium concentration in heterologous cells. In this study, we have characterized the second-messenger stimulation by endogenous DmAdoR in a Drosophila neuroblast cell line and examined a number of Ado analogs for their ability to interact with DmAdoR. We show that Ado can stimulate cAMP but not calcium levels in Drosophila cells. We found one full and four partial DmAdoR agonists, as well as four antagonists. The employment of the full agonist, 2-chloroadenosine, in flies mimicked in vivo the phenotype of DmAdoR over-expression, whereas the antagonist, SCH58261, rescued the flies from the lethality caused by DmAdoR over-expression. Differences in pharmacological effect of the tested analogs between DmAdoR and human A2AR can be partially explained by the dissimilarity of specific key amino acid residues disclosed by the alignment of these receptors.
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Affiliation(s)
- Lucie Kucerova
- Biology Centre Czech Acad. Sci. and Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
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Savelkoul PJM, Janickova H, Kuipers AAM, Hageman RJJ, Kamphuis PJ, Dolezal V, Broersen LM. A specific multi-nutrient formulation enhances M1 muscarinic acetylcholine receptor responses in vitro. J Neurochem 2012; 120:631-40. [PMID: 22146060 DOI: 10.1111/j.1471-4159.2011.07616.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Recent evidence indicates that supplementation with a specific combination of nutrients may affect cell membrane synthesis and composition. To investigate whether such nutrients may also modify the physical properties of membranes, and affect membrane-bound processes involved in signal transduction pathways, we studied the effects of nutrient supplementation on G protein-coupled receptor activation in vitro. In particular, we investigated muscarinic receptors, which are important for the progression of memory deterioration and pathology of Alzheimer's disease. Nerve growth factor differentiated pheochromocytoma cells that were supplemented with specific combinations of nutrients showed enhanced responses to muscarinic receptor agonists in a membrane potential assay. The largest effects were obtained with a combination of nutrients known as Fortasyn™ Connect, comprising docosahexaenoic acid, eicosapentaenoic acid, uridine monophosphate as a uridine source, choline, vitamin B6, vitamin B12, folic acid, phospholipids, vitamin C, vitamin E, and selenium. In subsequent experiments, it was shown that the effects of supplementation could not be attributed to single nutrients. In addition, it was shown that the agonist-induced response and the supplement-induced enhancement of the response were blocked with the muscarinic receptor antagonists atropine, telenzepine, and AF-DX 384. In order to determine whether the effects of Fortasyn™ Connect supplementation were receptor subtype specific, we investigated binding properties and activation of human muscarinic M1, M2 and M4 receptors in stably transfected Chinese hamster ovary cells after supplementation. Multi-nutrient supplementation did not change M1 receptor density in plasma membranes. However, M1 receptor-mediated G protein activation was significantly enhanced. In contrast, supplementation of M2- or M4-expressing cells did not affect receptor signaling. Taken together, these results indicate that a specific combination of nutrients acts synergistically in enhancing muscarinic M1 receptor responses, probably by facilitating receptor-mediated G protein activation.
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Affiliation(s)
- Paul J M Savelkoul
- Nutricia Advanced Medical Nutrition, Danone Research, Centre for Specialised Nutrition, Wageningen, The Netherlands.
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Zhang X, Gong Q, Zhang S, Wang L, Hu Y, Shen H, Dong S. 3-[3-(3-florophenyl-2-propyn-1-ylthio)-1, 2, 5-thiadiazol-4-yl]-1, 2, 5, 6-tetrahydro-1- methylpyridine oxalate, a novel xanomeline derivative, improves neural cells proliferation and survival in adult mice. Neural Regen Res 2012; 7:24-30. [PMID: 25806054 PMCID: PMC4354111 DOI: 10.3969/j.issn.1673-5374.2012.01.004] [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: 09/19/2011] [Accepted: 11/12/2011] [Indexed: 11/25/2022] Open
Abstract
The present study analyzed the influence of 3-[3-(3-florophenyl-2-propyn-1-ylthio)-1, 2, 5-thiadiazol-4-yl]-1, 2, 5, 6-tetrahydro-1-methylpyridine oxalate (EUK1001), a novel xanomeline derivative of the M1/M4 receptor agonist, on hippocampal neurogenesis in adult C57BL6 mice. Results showed that 15-day EUK1001 treatment via intraperitoneal injection promoted neural cell proliferation in the dentate gyrus, although cell differentiation did not change. The majority of bromodeoxyuridine-positive cells co-expressed the immature neuronal marker doublecortin. In addition, the level of neurogenesis in the subventricular zone was not altered. Brain-derived neurotrophic factor mRNA expression was up-regulated following EUK1001 treatment, but no change was observed in expression of camp-responsive element binding protein 1, paired box gene 6, vascular endothelial growth factor alpha, neurogenic differentiation factor 1, and wingless-related mouse mammary tumor virus integration site 3A mRNA. These experimental findings indicated that EUK1001 enhanced proliferation and survival of hippocampal cells, possibly by increasing brain-derived neurotrophic factor expression.
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Affiliation(s)
- Xiaoliang Zhang
- Key Laboratory of Brain Functional Genomics, Ministry of Education, East China Normal University, Shanghai 200062, China
| | - Qiang Gong
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
| | - Shuang Zhang
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
| | - Lin Wang
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
| | - Yinghe Hu
- Key Laboratory of Brain Functional Genomics, Ministry of Education, East China Normal University, Shanghai 200062, China ; Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
| | - Haiming Shen
- Institute of Aviation Medicine, Civil Aviation University of China, Tianjin 300300, China
| | - Suzhen Dong
- Key Laboratory of Brain Functional Genomics, Ministry of Education, East China Normal University, Shanghai 200062, China ; Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
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Jakubík J, Janíčková H, Randáková A, El-Fakahany EE, Doležal V. Subtype differences in pre-coupling of muscarinic acetylcholine receptors. PLoS One 2011; 6:e27732. [PMID: 22110745 PMCID: PMC3218020 DOI: 10.1371/journal.pone.0027732] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 10/24/2011] [Indexed: 11/18/2022] Open
Abstract
Based on the kinetics of interaction between a receptor and G-protein, a myriad of possibilities may result. Two extreme cases are represented by: 1/Collision coupling, where an agonist binds to the free receptor and then the agonist-receptor complex “collides” with the free G-protein. 2/Pre-coupling, where stable receptor/G-protein complexes exist in the absence of agonist. Pre-coupling plays an important role in the kinetics of signal transduction. Odd-numbered muscarinic acetylcholine receptors preferentially couple to Gq/11, while even-numbered receptors prefer coupling to Gi/o. We analyzed the coupling status of the various subtypes of muscarinic receptors with preferential and non-preferential G-proteins. The magnitude of receptor-G-protein coupling was determined by the proportion of receptors existing in the agonist high-affinity binding conformation. Antibodies directed against the C-terminus of the α-subunits of the individual G-proteins were used to interfere with receptor-G-protein coupling. Effects of mutations and expression level on receptor-G-protein coupling were also investigated. Tested agonists displayed biphasic competition curves with the antagonist [3H]-N-methylscopolamine. Antibodies directed against the C-terminus of the α-subunits of the preferential G-protein decreased the proportion of high-affinity sites, and mutations at the receptor-G-protein interface abolished agonist high-affinity binding. In contrast, mutations that prevent receptor activation had no effect. Expression level of preferential G-proteins had no effect on pre-coupling to non-preferential G-proteins. Our data show that all subtypes of muscarinic receptors pre-couple with their preferential classes of G-proteins, but only M1 and M3 receptors also pre-couple with non-preferential Gi/o G-proteins. Pre-coupling is not dependent on agonist efficacy nor on receptor activation. The ultimate mode of coupling is therefore dictated by a combination of the receptor subtype and the class of G-protein.
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Affiliation(s)
- Jan Jakubík
- Department of Neurochemistry, Institute of Physiology Academy of Sciences of the Czech Republic v.v.i., Prague, Czech Republic.
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Martino G, Puma C, Yu XH, Gilbert AK, Coupal M, Markoglou N, McIntosh FS, Perkins MN, Laird JMA. The M1/M4 preferring agonist xanomeline is analgesic in rodent models of chronic inflammatory and neuropathic pain via central site of action. Pain 2011; 152:2852-2860. [PMID: 22018972 DOI: 10.1016/j.pain.2011.09.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 08/11/2011] [Accepted: 09/16/2011] [Indexed: 10/16/2022]
Abstract
The role of muscarinic receptor subtype-1 (M1) in chronic pain is unclear. In an attempt to gain an understanding of its role, we have tested xanomeline, an M1/M4-preferring agonist, together with nonselective (scopolamine and pirenzepine), and selective (MT-7 and MT-3) muscarinic receptor (M1 and M4, respectively) antagonists in a number of inflammatory and neuropathic pain models. Xanomeline potently and effectively reversed tactile allodynia and heat hyperalgesia associated with established neuropathic and inflammatory pain in both rat and mouse models. Scopolamine and pirenzepine completely blocked the analgesic response to xanomeline, confirming that the analgesic effect is mediated by the muscarinic system. The highly selective M1 receptor toxin, MT-7, almost completely abolished the analgesic response to xanomeline when administered supraspinally. However, the highly selective M4 receptor toxin, MT-3, only marginally reversed the analgesia when given supraspinally, and had no effect when given spinally. In conclusion, the data presented show that the nonselective muscarinic agonist xanomeline is analgesic in models of persistent pain and suggest that the activation of supraspinal M1 receptors, and to a lesser extent supraspinal M4 receptors, contributes to that analgesia.
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Affiliation(s)
- Giovanni Martino
- AstraZeneca R&D Montreal, St-Laurent, QC, Canada Department of Pharmacology and Experimental Therapeutics, McGill University, Montreal, Canada Alan Edwards Centre for Research on Pain, McGill University, Montreal, Canada
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Involvement of a subpopulation of neuronal M4 muscarinic acetylcholine receptors in the antipsychotic-like effects of the M1/M4 preferring muscarinic receptor agonist xanomeline. J Neurosci 2011; 31:5905-8. [PMID: 21508215 DOI: 10.1523/jneurosci.0370-11.2011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Disturbances in central dopaminergic neurotransmission are believed to be centrally involved in the pathogenesis of schizophrenia. Central dopaminergic and cholinergic systems interact and the cholinergic muscarinic agonist xanomeline has shown antipsychotic effects in clinical studies. Preclinical studies indicate that the M(4) muscarinic cholinergic receptor subtype (mAChR) modulates the activity of the dopaminergic system and that this specific mAChR subtype is involved in mediating the antipsychotic-like effects of xanomeline. A specific neuronal subpopulation that expresses M(4) mAChRs together with D(1) dopamine receptors seems to be especially important in modulating dopamine-dependent behaviors. Using mutant mice that lack the M(4) mAChR only in D(1) dopamine receptor-expressing cells (D1-M4-KO), we investigated the role of this neuronal population in the antipsychotic-like effects of xanomeline in amphetamine-induced hyperactivity and apomorphine-induced climbing. Interestingly, the antipsychotic-like effects of xanomeline in the two models were almost completely abolished in D1-M4-KO mice, suggesting that M(4) mAChRs colocalized with D(1) dopamine receptors are centrally involved in mediating the antipsychotic-like effects of xanomeline. This is consistent with the hypothesis that activation of the M(4) mAChR represents a potential target for the future medical treatment of psychosis.
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Lyukmanova EN, Shenkarev ZO, Shulepko MA, Mineev KS, D'Hoedt D, Kasheverov IE, Filkin SY, Krivolapova AP, Janickova H, Dolezal V, Dolgikh DA, Arseniev AS, Bertrand D, Tsetlin VI, Kirpichnikov MP. NMR structure and action on nicotinic acetylcholine receptors of water-soluble domain of human LYNX1. J Biol Chem 2011; 286:10618-27. [PMID: 21252236 PMCID: PMC3060513 DOI: 10.1074/jbc.m110.189100] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 12/20/2010] [Indexed: 12/26/2022] Open
Abstract
Discovery of proteins expressed in the central nervous system sharing the three-finger structure with snake α-neurotoxins provoked much interest to their role in brain functions. Prototoxin LYNX1, having homology both to Ly6 proteins and three-finger neurotoxins, is the first identified member of this family membrane-tethered by a GPI anchor, which considerably complicates in vitro studies. We report for the first time the NMR spatial structure for the water-soluble domain of human LYNX1 lacking a GPI anchor (ws-LYNX1) and its concentration-dependent activity on nicotinic acetylcholine receptors (nAChRs). At 5-30 μM, ws-LYNX1 competed with (125)I-α-bungarotoxin for binding to the acetylcholine-binding proteins (AChBPs) and to Torpedo nAChR. Exposure of Xenopus oocytes expressing α7 nAChRs to 1 μM ws-LYNX1 enhanced the response to acetylcholine, but no effect was detected on α4β2 and α3β2 nAChRs. Increasing ws-LYNX1 concentration to 10 μM caused a modest inhibition of these three nAChR subtypes. A common feature for ws-LYNX1 and LYNX1 is a decrease of nAChR sensitivity to high concentrations of acetylcholine. NMR and functional analysis both demonstrate that ws-LYNX1 is an appropriate model to shed light on the mechanism of LYNX1 action. Computer modeling, based on ws-LYNX1 NMR structure and AChBP x-ray structure, revealed a possible mode of ws-LYNX1 binding.
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Affiliation(s)
- Ekaterina N. Lyukmanova
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Zakhar O. Shenkarev
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Mikhail A. Shulepko
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Konstantin S. Mineev
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Dieter D'Hoedt
- the Department of Neuroscience, Centre Medical Universitaire, 1 Rue Michel Servet, 1211 Geneva 4, Switzerland
| | - Igor E. Kasheverov
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Sergey Yu. Filkin
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Alexandra P. Krivolapova
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Helena Janickova
- the Institute of Physiology, Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic, and
| | - Vladimir Dolezal
- the Institute of Physiology, Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic, and
| | - Dmitry A. Dolgikh
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
- Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Alexander S. Arseniev
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Daniel Bertrand
- the Department of Neuroscience, Centre Medical Universitaire, 1 Rue Michel Servet, 1211 Geneva 4, Switzerland
| | - Victor I. Tsetlin
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Mikhail P. Kirpichnikov
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
- Lomonosov Moscow State University, 119991 Moscow, Russia
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Jakubík J, Janíčková H, El-Fakahany EE, Doležal V. Negative cooperativity in binding of muscarinic receptor agonists and GDP as a measure of agonist efficacy. Br J Pharmacol 2011; 162:1029-44. [PMID: 20958290 PMCID: PMC3051377 DOI: 10.1111/j.1476-5381.2010.01081.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 08/23/2010] [Accepted: 09/22/2010] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Conventional determination of agonist efficacy at G-protein coupled receptors is measured by stimulation of guanosine-5'-γ-thiotriphosphate (GTPγS) binding. We analysed the role of guanosine diphosphate (GDP) in the process of activation of the M₂ muscarinic acetylcholine receptor and provide evidence that negative cooperativity between agonist and GDP binding is an alternative measure of agonist efficacy. EXPERIMENTAL APPROACH Filtration and scintillation proximity assays measured equilibrium binding as well as binding kinetics of [³⁵S]GTPγS and [³H]GDP to a mixture of G-proteins as well as individual classes of G-proteins upon binding of structurally different agonists to the M₂ muscarinic acetylcholine receptor. KEY RESULTS Agonists displayed biphasic competition curves with the antagonist [³H]-N-methylscopolamine. GTPγS (1 µM) changed the competition curves to monophasic with low affinity and 50 µM GDP produced a similar effect. Depletion of membrane-bound GDP increased the proportion of agonist high-affinity sites. Carbachol accelerated the dissociation of [³H]GDP from membranes. The inverse agonist N-methylscopolamine slowed GDP dissociation and GTPγS binding without changing affinity for GDP. Carbachol affected both GDP association with and dissociation from G(i/o) G-proteins but only its dissociation from G(s/olf) G-proteins. CONCLUSIONS AND IMPLICATIONS These findings suggest the existence of a low-affinity agonist-receptor conformation complexed with GDP-liganded G-protein. Also the negative cooperativity between GDP and agonist binding at the receptor/G-protein complex determines agonist efficacy. GDP binding reveals differences in action of agonists versus inverse agonists as well as differences in activation of G(i/o) versus G(s/olf) G-proteins that are not identified by conventional GTPγS binding.
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Affiliation(s)
- J Jakubík
- Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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Grant MKO, Noetzel MJ, De Lorme KC, Jakubík J, Doležal V, El-Fakahany EE. Pharmacological evaluation of the long-term effects of xanomeline on the M(1) muscarinic acetylcholine receptor. PLoS One 2010; 5:e15722. [PMID: 21203415 PMCID: PMC3009740 DOI: 10.1371/journal.pone.0015722] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 11/28/2010] [Indexed: 11/19/2022] Open
Abstract
Xanomeline is a unique agonist of muscarinic receptors that possesses functional selectivity at the M1 and M4 receptor subtypes. It also exhibits wash-resistant binding to and activation of the receptor. In the present work we investigated the consequences of this type of binding of xanomeline on the binding characteristics and function of the M1 muscarinic receptor. Pretreatment of CHO cells that stably express the M1 receptor for 1 hr with increasing concentrations of xanomeline followed by washing and waiting for an additional 23 hr in control culture media transformed xanomeline-induced inhibition of [3H]NMS binding from monophasic to biphasic. The high-affinity xanomeline binding site exhibited three orders of magnitude higher affinity than in the case of xanomeline added directly to the binding assay medium containing control cells. These effects were associated with a marked decrease in maximal radioligand binding and attenuation of agonist-induced increase in PI hydrolysis and were qualitatively similar to those caused by continuous incubation of cells with xanomeline for 24 hr. Attenuation of agonist-induced PI hydrolysis by persistently-bound xanomeline developed with a time course that parallels the return of receptor activation by prebound xanomeline towards basal levels. Additional data indicated that blockade of the receptor orthosteric site or the use of a non-functional receptor mutant reversed the long-term effects of xanomeline, but not its persistent binding at an allosteric site. Furthermore, the long-term effects of xanomeline on the receptor are mainly due to receptor down-regulation rather than internalization.
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Affiliation(s)
- Marianne K. O. Grant
- Department of Psychiatry, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Meredith J. Noetzel
- Department of Psychiatry, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Kayla C. De Lorme
- Department of Psychiatry, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Jan Jakubík
- Department of Neurochemistry, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
- * E-mail:
| | - Vladimír Doležal
- Department of Neurochemistry, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Esam E. El-Fakahany
- Department of Psychiatry, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
- Department of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
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Digby GJ, Shirey JK, Conn PJ. Allosteric activators of muscarinic receptors as novel approaches for treatment of CNS disorders. MOLECULAR BIOSYSTEMS 2010; 6:1345-54. [PMID: 20582339 PMCID: PMC4780333 DOI: 10.1039/c002938f] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Muscarinic acetylcholine receptors (mAChRs) represent exciting therapeutic targets for the treatment of multiple CNS disorders. The high degree of conservation of amino acids comprising the orthosteric acetylcholine (ACh) binding site between individual mAChR subtypes has hindered the development of subtype-selective compounds that bind to this site. As a result, many academic and industry researchers are now focusing on developing allosteric activators of mAChRs including both positive allosteric modulators (PAMs) and allosteric agonists. In the past 10 years major advances have been achieved in the discovery of allosteric ligands that possess much greater selectivity for individual mAChR subtypes when compared to previously developed orthosteric agents. These novel allosteric modulators of mAChRs may provide therapeutic potential for treatment of a number of CNS disorders such as Alzheimer's disease and schizophrenia.
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Affiliation(s)
- Gregory J. Digby
- 1215 Light Hall, 2215B Garland Ave., Nashville, TN 37237-0575, USA. ; Fax: +1 615 343 3088; Tel: +1 615 322 6730
| | - Jana K. Shirey
- 8410E Medical Research Building IV, 2215B Garland Ave., Nashville, TN 37237-0575, USA. ; Fax: +1 615 936-2661; Tel: +1 615 936-8424
| | - P. Jeffrey Conn
- 2215B Garland Ave., Nashville, TN 37237-0575, USA. ; Fax: +1 615 343 3088; Tel: +1 615 322 6730
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Machová E, Rudajev V, Smycková H, Koivisto H, Tanila H, Dolezal V. Functional cholinergic damage develops with amyloid accumulation in young adult APPswe/PS1dE9 transgenic mice. Neurobiol Dis 2010; 38:27-35. [PMID: 20053373 DOI: 10.1016/j.nbd.2009.12.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 12/03/2009] [Accepted: 12/26/2009] [Indexed: 10/20/2022] Open
Abstract
We investigated the functional characteristics of pre- and postsynaptic cholinergic transmission in APPswe/PS1dE9 double transgenic mice at a young age (7-10 weeks) before the onset of amyloid plaque formation and at adult age (5-6 months) at its onset. We compared brain slices from cerebral cortex and hippocampus with amyloid deposits to slices from striatum with no amyloid plaques by 6 months of age. In young transgenic mice we found no impairments of preformed and newly synthesized [(3)H]-ACh release, indicating intact releasing machinery and release turnover, respectively. Adult transgenic mice displayed a significant increase in preformed [(3)H]-ACh release in cortex but a decrease in hippocampus and striatum. The extent of presynaptic muscarinic autoregulation was unchanged. Evoked release of newly synthesized [(3)H]-ACh was significantly reduced in the cortex and hippocampus but unchanged in the striatum. Carbachol-induced G-protein activation in cortical membranes displayed decreased potency but normal efficacy in adult animals and no changes in young animals. These results indicate that functional pre- and postsynaptic cholinergic deficits are not present in APPswe/PS1dE9 transgenic mice before 10 weeks of age, but develop along with beta-amyloid accumulation in the brain.
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Affiliation(s)
- Eva Machová
- Institute of Physiology CAS, Vídenská 1083, 14220 Prague 4, Czech Republic
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Jakubík J, Randáková A, El-Fakahany EE, Dolezal V. Divergence of allosteric effects of rapacuronium on binding and function of muscarinic receptors. BMC Pharmacol 2009; 9:15. [PMID: 20038295 PMCID: PMC2806265 DOI: 10.1186/1471-2210-9-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Accepted: 12/28/2009] [Indexed: 12/02/2022] Open
Abstract
Background Many neuromuscular blockers act as negative allosteric modulators of muscarinic acetylcholine receptors by decreasing affinity and potency of acetylcholine. The neuromuscular blocker rapacuronium has been shown to have facilitatory effects at muscarinic receptors leading to bronchospasm. We examined the influence of rapacuronium on acetylcholine (ACh) binding to and activation of individual subtypes of muscarinic receptors expressed in Chinese hamster ovary cells to determine its receptor selectivity. Results At equilibrium rapacuronium bound to all subtypes of muscarinic receptors with micromolar affinity (2.7-17 μM) and displayed negative cooperativity with both high- and low-affinity ACh binding states. Rapacuronium accelerated [3H]ACh association with and dissociation from odd-numbered receptor subtypes. With respect to [35S]GTPγS binding rapacuronium alone behaved as an inverse agonist at all subtypes. Rapacuronium concentration-dependently decreased the potency of ACh-induced [35S]GTPγS binding at M2 and M4 receptors. In contrast, 0.1 μM rapacuronium significantly increased ACh potency at M1, M3, and M5 receptors. Kinetic measurements at M3 receptors showed acceleration of the rate of ACh-induced [35S]GTPγS binding by rapacuronium. Conclusions Our data demonstrate a novel dichotomy in rapacuronium effects at odd-numbered muscarinic receptors. Rapacuronium accelerates the rate of ACh binding but decreases its affinity under equilibrium conditions. This results in potentiation of receptor activation at low concentrations of rapacuronium (1 μM) but not at high concentrations (10 μM). These observations highlight the relevance and necessity of performing physiological tests under non-equilibrium conditions in evaluating the functional effects of allosteric modulators at muscarinic receptors. They also provide molecular basis for potentiating M3 receptor-mediated bronchoconstriction.
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Affiliation(s)
- Jan Jakubík
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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Davis CN, Bradley SR, Schiffer HH, Friberg M, Koch K, Tolf BR, Bonhaus DW, Lameh J. Differential regulation of muscarinic M1 receptors by orthosteric and allosteric ligands. BMC Pharmacol 2009; 9:14. [PMID: 19951444 PMCID: PMC2794843 DOI: 10.1186/1471-2210-9-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Accepted: 12/02/2009] [Indexed: 11/13/2022] Open
Abstract
Background Activation of muscarinic M1 receptors is mediated via interaction of orthosteric agonists with the acetylcholine binding site or via interaction of allosteric agonists with different site(s) on the receptor. The focus of the present study was to determine if M1 receptors activated by allosteric agonists undergo the same regulatory fate as M1 receptors activated by orthosteric agonists. Results The orthosteric agonists carbachol, oxotremorine-M and pilocarpine were compared to the allosteric agonists AC-42, AC-260584, N-desmethylclozapine and xanomeline. All ligands activated M1 receptors and stimulated interaction of the receptors with β-arrestin-1. All ligands reduced cell surface binding and induced the loss of total receptor binding. Receptor internalization was blocked by treatment with hypertonic sucrose indicating that all ligands induced formation of clathrin coated vesicles. However, internalized receptors recycled to the cell surface following removal of orthosteric, but not allosteric agonists. Whereas all ligands induced loss of cell surface receptor binding, no intracellular vesicles could be observed after treatment with AC-260584 or xanomeline. Brief stimulation of M1 receptors with AC-260584 or xanomeline resulted in persistent activation of M1 receptors, suggesting that continual receptor signaling might impede or delay receptor endocytosis into intracellular vesicles. Conclusion These results indicate that allosteric agonists differ from orthosteric ligands and among each other in their ability to induce different regulatory pathways. Thus, signaling and regulatory pathways induced by different allosteric ligands are ligand specific.
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Affiliation(s)
- Christopher N Davis
- ACADIA Pharmaceuticals Inc, 3911 Sorrento Valley Blvd, San Diego, CA 92121, USA.
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Mordvintsev DY, Polyak YL, Rodionov DI, Jakubik J, Dolezal V, Karlsson E, Tsetlin VI, Utkin YN. Weak toxin WTX from Naja kaouthia cobra venom interacts with both nicotinic and muscarinic acetylcholine receptors. FEBS J 2009; 276:5065-75. [PMID: 19682302 DOI: 10.1111/j.1742-4658.2009.07203.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Iodinated [125I] weak toxin from Naja kaouthia (WTX) cobra venom was injected into mice, and organ-specific binding was monitored. Relatively high levels of [125I]WTX were detected in the adrenal glands. Rat adrenal membranes were therefore used for analysis of [125I]WTX-binding sites. Specific [125I]WTX binding was partially inhibited by both alpha-cobratoxin, a blocker of the alpha7 and muscle-type nicotinic acetylcholine receptors (nAChRs), and by atropine, an antagonist of the muscarinic acetylcholine receptor (mAChR). Binding to rat adrenal nAChR had a Kd of 2.0+/-0.8 microM and was inhibited by alpha-cobratoxin but not by a short-chain alpha-neurotoxin antagonist of the muscle-type nAChR, suggesting a specific interaction with the alpha7-type nAChR. WTX binding was reduced not only by atropine but also by other muscarinic agents (oxotremorine and muscarinic toxins from Dendroaspis angusticeps), indicating an interaction with mAChR. This interaction was further characterized using individual subtypes of human mAChRs expressed in Chinese hamster ovary cells. WTX concentrations up to 30 microM did not inhibit binding of [3H]acetylcholine to any subtype of mAChR by more than 50%. Depending on receptor subtype, WTX either increased or had no effect on the binding of the muscarinic antagonist [3H]N-methylscopolamine, which binds to the orthosteric site, a finding indicative of an allosteric interaction. Furthermore, WTX alone activated G-protein coupling with all mAChR subtypes and reduced the efficacy of acetylcholine in activating G-proteins with the M1, M4, and M5 subtypes. Our data demonstrate an orthosteric WTX interaction with nAChR and an allosteric interaction with mAChRs.
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Membrane cholesterol content influences binding properties of muscarinic M2 receptors and differentially impacts activation of second messenger pathways. Eur J Pharmacol 2009; 606:50-60. [PMID: 19374848 DOI: 10.1016/j.ejphar.2009.01.028] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 01/06/2009] [Accepted: 01/19/2009] [Indexed: 11/22/2022]
Abstract
We investigated the influence of membrane cholesterol content on preferential and non-preferential signaling through the M(2) muscarinic acetylcholine receptor expressed in CHO cells. Cholesterol depletion by 39% significantly decreased the affinity of M(2) receptors for [(3)H]-N-methylscopolamine ([(3)H]-NMS) binding and increased B(max) in intact cells and membranes. Membranes displayed two-affinity agonist binding sites for carbachol and cholesterol depletion doubled the fraction of high-affinity binding sites. In intact cells it also reduced the rate of agonist-induced receptor internalization and changed the profile of agonist binding from a single site to two affinity states. Cholesterol enrichment by 137% had no effects on carbachol E(max) of cAMP synthesis inhibition and on cAMP synthesis stimulation and inositolphosphates (IP) accumulation at higher agonist concentrations (non-preferred pathways). On the other hand, cholesterol depletion significantly increased E(max) of cAMP synthesis inhibition or stimulation without change in potency, and decreased E(max) of IP accumulation. Noteworthy, modifications of membrane cholesterol had no effect on membrane permeability, oxidative activity, protein content, or relative expression of G(s), G(i/o), and G(q/11) alpha subunits. These results demonstrate distinct changes of M(2) receptor signaling through both preferential and non-preferential G-proteins consequent to membrane cholesterol depletion that occur at the level of receptor/G-protein/effector protein interactions in the cell membrane. The significant decrease of IP accumulation by cholesterol depletion was also observed in cells expressing M(3) receptors and by both cholesterol depletion and enrichment in cells expressing M(1) receptors indicating relevance of reduced G(q/11) signaling for the pathogenesis of Alzheimer's disease.
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Noetzel MJ, Grant MKO, El-Fakahany EE. Immediate and delayed consequences of xanomeline wash-resistant binding at the M3 muscarinic receptor. Neurochem Res 2008; 34:1138-49. [PMID: 19082883 DOI: 10.1007/s11064-008-9886-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2008] [Indexed: 10/21/2022]
Abstract
Xanomeline is thought to be a M1/M4 functionally selective agonist at muscarinic receptors. We have previously demonstrated that it binds in a unique manner at the M1 receptor. In the current study, we examined the ability of xanomeline to bind to the M3 receptor and determined the long-term consequences of this mode of binding in Chinese hamster ovary cells expressing M3 receptors. Xanomeline binds in a reversible and wash-resistant manner at the M3 receptor and elicits a functional response under both conditions. Long-term exposure to xanomeline resulted in changes in the binding profile of [(3)H]NMS and a decrease in cell-surface receptor density. Additionally, pretreatment with xanomeline was associated with antagonism of the functional response to subsequent stimulation by conventional agonists. Our results indicate that xanomeline binds to and activates the M3 muscarinic receptor in a wash-resistant manner, and that this type of binding results in time-dependent receptor regulation.
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Affiliation(s)
- Meredith J Noetzel
- Division of Neuroscience Research in Psychiatry, Department of Psychiatry, University of Minnesota Medical School, Minneapolis, MN 55455, USA
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42
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Nathaniel TI, Umesiri FE, Olajuyigbe F. Role of M1 receptor in the locomotion behavior of the African mole-rat (Cryptomys sp). J Integr Neurosci 2008; 7:1-16. [PMID: 18431815 DOI: 10.1142/s021963520800168x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 02/11/2008] [Indexed: 01/14/2023] Open
Abstract
Studies exploring the endogenous mechanism that modulates locomotion in Cryptomys sp, a bathyergid of the subterranean hystricomorph African mole-rat species might contribute to the understanding of the interrelations between external variables and internal mechanisms that controls the diverse patterns of locomotion in mole-rats. It has been shown that environmental variables contribute to the inter-individual variations in the daily patterns of locomotion, however, it is not well known if endogenous mechanism such as M1 receptor that regulates locomotion in surface dwelling rodents could as well regulate locomotion in the subterranean dwelling rodent. The present study explores this issue in Cryptomys sp a subterranean African mole-rat species. Using both specific and non-specific antagonists and agonists of M1 receptor, we manipulated the centrally expressed M1 receptor activity and characterized the effects of such manipulations on locomotor activity of Cryptomys sp. Our results indicate that infusion of M1 receptor specific and non-specific antagonists into the left or right ventricle impaired translatory movements, resulting in the display of abnormal complex rotatory locomotion. Based on the findings of this study, we suggest that M1 receptor activity might be part of the endogenous mechanisms that regulate the locomotor activity of Cryptomys sp.
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Affiliation(s)
- Thomas I Nathaniel
- Center for Natural and Health Sciences, Science Department, Marywood University, 2300 Adams Ave., Scranton, PA 18509, USA.
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De Lorme KC, Grant MKO, Noetzel MJ, Polson SB, El-Fakahany EE. Long-term changes in the muscarinic M1 receptor induced by instantaneous formation of wash-resistant xanomeline-receptor complex. J Pharmacol Exp Ther 2007; 323:868-76. [PMID: 17855477 DOI: 10.1124/jpet.107.129940] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Unlike other M1 muscarinic acetylcholine receptor agonists, xanomeline demonstrates a unique mode of binding to the receptor. It not only binds reversibly to the receptor's conventional orthosteric site but also binds persistently at a secondary binding domain(s) on the M1 receptor. This results in persistent activation of the receptor even after extensive washout, and allosteric modulation of the orthosteric site. In the current study, we investigated how the effects of very brief exposure (1 min) of intact Chinese hamster ovary cells expressing M1 receptors to xanomeline followed by washout change with time. Pretreatment with xanomeline for 1 min resulted in a concentration-dependent wash-resistant inhibition of [3H]N-methylscopolamine (NMS) binding, with a lower potency than that observed in the continuous presence of xanomeline in the binding assay medium. This effect was associated with wash-resistant receptor activation. Incubation of pretreated and washed cells in control medium for 24 h transformed the monophasic xanomeline wash-resistant binding curve to one that exhibits two distinct potencies. This was the result of the appearance of a new very high-potency binding component without a change in the low-potency state. The delayed effects of persistently bound xanomeline are mainly due to reduction of the maximal binding of [3H]NMS without a change in its affinity. These treatment conditions also reversed persistent receptor activation by xanomeline. Our results imply that brief exposure to xanomeline followed by washing and prolonged waiting may result in delayed receptor desensitization accompanied by internalization or down-regulation.
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Affiliation(s)
- Kayla C De Lorme
- Division of Neuroscience Research in Psychiatry, University of Minnesota Medical School, Minneapolis, MN 55455, USA
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Machová E, Jakubík J, El-Fakahany EE, Dolezal V. Wash-resistantly bound xanomeline inhibits acetylcholine release by persistent activation of presynaptic M(2) and M(4) muscarinic receptors in rat brain. J Pharmacol Exp Ther 2007; 322:316-23. [PMID: 17446301 DOI: 10.1124/jpet.107.122093] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We studied the effects of 3-[3-hexyloxy-1,2,5-thiadiazo-4-yl]-1,2,5,6-tetrahydro-1-methylpyridine (xanomeline) wash-resistant binding on presynaptic muscarinic regulation of electrically evoked [(3)H]acetylcholine (ACh) release from rat brain slices. In both cortical and striatal tissues that possess M(2) and M(4) autoreceptors, respectively, immediate application of 10 microM xanomeline had no effect on evoked [(3)H]ACh release or its inhibition by 10 microM carbachol. In contrast, preincubation with 1, 10, or 100 microM xanomeline for 15 min decreased evoked release of ACh measured after 53 min of washing in xanomeline-free medium in a concentration-dependent manner. The maximal inhibitory effect equaled the immediate effect of the muscarinic full agonist carbachol, and it was completely (at 1 and 10 microM xanomeline) or partially (at 100 microM xanomeline) blocked by 1 microM N-methylscopolamine. Neither presence of N-methylscopolamine during 100 microM xanomeline treatment nor previous irreversible inactivation of the classical receptor binding site using propylbenzylcholine mustard in cortical slices prevented the inhibitory effect of wash-resistantly bound xanomeline. Treatment of cortical slices with xanomeline slightly decreased the number of muscarinic binding sites, and it markedly decreased affinity for N-methylscopolamine. When applied as in acetylcholine release experiments, xanomeline did not impair presynaptic alpha(2)-adrenoceptor-mediated regulation of noradrenaline release. The functional studies in brain tissue reported in this work demonstrate that xanomeline can function as a wash-resistant agonist of native presynaptic muscarinic M(2) and M(4) receptors with both competitive and allosteric components of action.
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Affiliation(s)
- E Machová
- Institute of Physiology, Czech Academy of Sciences, Vídenská 1083, 14220 Prague, Czech Republic
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Machová E, Jakubík J, Michal P, Oksman M, Iivonen H, Tanila H, Dolezal V. Impairment of muscarinic transmission in transgenic APPswe/PS1dE9 mice. Neurobiol Aging 2006; 29:368-78. [PMID: 17140703 DOI: 10.1016/j.neurobiolaging.2006.10.029] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 09/20/2006] [Accepted: 10/30/2006] [Indexed: 02/07/2023]
Abstract
We assessed the integrity of cholinergic neurotransmission in parietal cortex of young adult (7 months) and aged (17 months) transgenic APPswe/PS1dE9 female mice compared to littermate controls. Choline acetyltransferase and acetylcholinesterase activity declined age-dependently in both genotypes, whereas both age- and genotype-dependent decline was found in butyrylcholinesterase activity, vesicular acetylcholine transporter density, muscarinic receptors and carbachol stimulated binding of GTP gamma S in membranes as a functional indicator of muscarinic receptor coupling to G-proteins. Notably, vesicular acetylcholine transporter levels and muscarinic receptor-G-protein coupling were impaired in transgenic mice already at the age of 7 months compared to wild type littermates. Thus, brain amyloid accumulation in this mouse model is accompanied by a serious deterioration of muscarinic transmission already before the mice manifest significant cognitive deficits.
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Affiliation(s)
- E Machová
- Department of Neurochemistry, Institute of Physiology CAS, Vídenská 1083, 14220 Prague 4, Czech Republic
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Michal P, El-Fakahany EE, Dolezal V. Muscarinic M2 receptors directly activate Gq/11 and Gs G-proteins. J Pharmacol Exp Ther 2006; 320:607-14. [PMID: 17065363 DOI: 10.1124/jpet.106.114314] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Muscarinic M(2) receptors preferentially couple with the G(i/o) class of G-proteins to inhibit cAMP synthesis. However, they can also stimulate net synthesis of cAMP and inositol phosphate (IP) accumulation. We investigated in intact Chinese hamster ovary (CHO) cells expressing human M(2) receptors (CHO-M(2) cells) whether direct interaction of M(2) receptors with G(s) and G(q/11) G-proteins is responsible for the latter effects. Suppression of the G(s)alpha subunit using RNA interference abolished stimulation of cAMP synthesis induced by 1 mM carbachol in both control and pertussis toxin-treated CHO-M(2) cells but had no effect on the inhibition of forskolin-stimulated cAMP synthesis. Carbachol stimulated accumulation of IP with an EC(50) of 79 microM. Removal of the G(q),G(11), or both alpha subunits reduced this response by 78, 54, and 92%, respectively, whereas suppression of the G(s)alpha subunit had no effect. Similar results obtained in CHO cells expressing M(1) receptors that preferentially couple with G(s) and G(q/11) G-proteins confirmed the efficiency of siRNA treatments. Stimulation of M(2) receptors in control and pertussis toxin-treated cells by a series of full agonists with respect to inhibition of adenylyl cyclase displayed different efficacies in stimulating IP accumulation. Carbachol, acetylcholine, and oxotremorine-M [N,N,N-trimethyl-4-(2-oxo-1-pyrolidinyl)-2-butyn-1-ammonium] behaved as full agonists, furmethide (N,N,N-trimethyl-2-furanmethammonium) and methylfurmethide [(5-methyl-2-furyl)methyltrimethylammonium] were partial agonists, and oxotremorine (1-[4-(1-pyrrolidinyl)-2-butynyl]-2-pyrrolidinone) had no effect. Our results provide direct evidence of M(2) receptor coupling with the alpha subunits of G(s) and G(q/11) G-proteins and demonstrate induction of multiple receptor conformational states dependent on both the concentration and the nature of the agonist used.
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Affiliation(s)
- P Michal
- Institute of Physiology CAS, Vídenská 1083, 14220 Prague, Czech Republic
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De Lorme KC, Sikorski KL, Grant MKO, El-Fakahany EE. Long-term wash-resistant effects of brief interaction of xanomeline at the M1 muscarinic receptor. Neurosci Lett 2006; 410:11-4. [PMID: 17052840 PMCID: PMC1850384 DOI: 10.1016/j.neulet.2006.09.062] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 09/21/2006] [Accepted: 09/23/2006] [Indexed: 11/28/2022]
Abstract
Compared to other M(1) muscarinic acetylcholine receptor (M(1) mAChR) agonists, xanomeline demonstrates both reversible and persistent modes of binding to the receptor. In our study, we investigated the long-term consequences of brief incubation of Chinese hamster ovary cells expressing M(1) mAChR (M(1)-CHO) with low concentrations of xanomeline followed by washing off the free drug. Thus, M(1)-CHO cells were exposed to 100 nM xanomeline for 1h then washed extensively. Washed cells were either used immediately for binding assays or incubated for 23 h in the absence of free xanomeline. Only the latter treatment conditions resulted in marked attenuation of binding of the muscarinic radioligand [(3)H]N-methylscopolamine ([(3)H]NMS) to intact cells. Shortening the xanomeline pretreatment period to 1 min had the same trends as the 1h pretreatment, implying that xanomeline binds instantly to the receptor to elicit long-term wash-resistant effects. Presence of atropine during the brief period of xanomeline pretreatment did not markedly modulate xanomeline's long-term effects, which suggests that persistent anchoring of the xanomeline molecule to the M(1) receptor takes place at a site distinct from the orthosteric binding domain. Our findings suggest the possibility of a time-dependent transition of the conformation of the muscarinic M(1) receptor-xanomeline complex between states that vary in their ability to bind [(3)H]NMS. However, possible involvement of other mechanisms of long-term receptor regulation cannot be discounted.
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Affiliation(s)
- Kayla C De Lorme
- Division of Neuroscience Research in Psychiatry, University of Minnesota Medical School, Mayo Mail Code 392, 420 Delaware St. SE, Minneapolis, MN 55455, USA
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