Abstract
Bivalent ligands of G protein-coupled receptors have been shown to simultaneously either bind to two adjacent receptors or to bridge different parts of one receptor protein. Recently, we found that bivalent agonists of muscarinic receptors can simultaneously occupy both the orthosteric transmitter binding site and the allosteric vestibule of the receptor protein. Such dualsteric agonists display a certain extent of subtype selectivity, generate pathway-specific signaling, and in addition may allow for designed partial agonism. Here, we want to extend the concept to bivalent antagonism. Using the phthal- and naphthalimide moieties, which bind to the allosteric, extracellular site, and atropine or scopolamine as orthosteric building blocks, both connected by a hexamethonium linker, we were able to prove a bitopic binding mode of antagonist hybrids for the first time. This is demonstrated by structure-activity relationships, site-directed mutagenesis, molecular docking studies, and molecular dynamics simulations. Findings revealed that a difference in spatial orientation of the orthosteric tropane moiety translates into a divergent M2/M5 subtype selectivity of the corresponding bitopic hybrids.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Allosteric Regulation
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Animals
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Atropine Derivatives / chemical synthesis
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Atropine Derivatives / chemistry*
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Atropine Derivatives / pharmacology
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Binding Sites
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CHO Cells
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Cricetulus
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Drug Inverse Agonism
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Humans
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Molecular Conformation
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Molecular Docking Simulation
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Molecular Dynamics Simulation
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Muscarinic Agonists / chemical synthesis
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Muscarinic Agonists / chemistry
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Muscarinic Agonists / pharmacology
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Muscarinic Antagonists / chemical synthesis
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Muscarinic Antagonists / chemistry*
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Muscarinic Antagonists / pharmacology
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Mutation
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Naphthalimides / chemical synthesis
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Naphthalimides / chemistry*
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Naphthalimides / pharmacology
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Phthalimides / chemical synthesis
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Phthalimides / chemistry*
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Phthalimides / pharmacology
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Radioligand Assay
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Receptor, Muscarinic M2 / agonists
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Receptor, Muscarinic M2 / antagonists & inhibitors
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Receptor, Muscarinic M2 / genetics
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Scopolamine Derivatives / chemical synthesis
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Scopolamine Derivatives / chemistry*
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Scopolamine Derivatives / pharmacology
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Stereoisomerism
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Structure-Activity Relationship
Substances
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Atropine Derivatives
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Muscarinic Agonists
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Muscarinic Antagonists
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Naphthalimides
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Phthalimides
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Receptor, Muscarinic M2
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Scopolamine Derivatives