25
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Putative Kappa Opioid Heteromers As Targets for Developing Analgesics Free of Adverse Effects

      research-article

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          It is now generally recognized that upon activation by an agonist, β-arrestin associates with G protein-coupled receptors and acts as a scaffold in creating a diverse signaling network that could lead to adverse effects. As an approach to reducing side effects associated with κ opioid agonists, a series of β-naltrexamides 310 was synthesized in an effort to selectively target putative κ opioid heteromers without recruiting β-arrestin upon activation. The most potent derivative 3 (INTA) strongly activated KOR-DOR and KOR-MOR heteromers in HEK293 cells. In vivo studies revealed 3 to produce potent antinociception, which, when taken together with antagonism data, was consistent with the activation of both heteromers. 3 was devoid of tolerance, dependence, and showed no aversive effect in the conditioned place preference assay. As immunofluorescence studies indicated no recruitment of β-arrestin2 to membranes in coexpressed KOR-DOR cells, this study suggests that targeting of specific putative heteromers has the potential to identify leads for analgesics devoid of adverse effects.

          Related collections

          Most cited references66

          • Record: found
          • Abstract: found
          • Article: not found

          Mu-opioid receptor desensitization by beta-arrestin-2 determines morphine tolerance but not dependence.

          Morphine is a powerful pain reliever, but also a potent inducer of tolerance and dependence. The development of opiate tolerance occurs on continued use of the drug such that the amount of drug required to elicit pain relief must be increased to compensate for diminished responsiveness. In many systems, decreased responsiveness to agonists has been correlated with the desensitization of G-protein-coupled receptors. In vitro evidence indicates that this process involves phosphorylation of G-protein-coupled receptors and subsequent binding of regulatory proteins called beta-arrestins. Using a knockout mouse lacking beta-arrestin-2 (beta arr2-/-), we have assessed the contribution of desensitization of the mu-opioid receptor to the development of morphine antinociceptive tolerance and the subsequent onset of physical dependence. Here we show that in mice lacking beta-arrestin-2, desensitization of the mu-opioid receptor does not occur after chronic morphine treatment, and that these animals fail to develop antinociceptive tolerance. However, the deletion of beta-arrestin-2 does not prevent the chronic morphine-induced up-regulation of adenylyl cyclase activity, a cellular marker of dependence, and the mutant mice still become physically dependent on the drug.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Molecular mechanism of β-arrestin-biased agonism at seven-transmembrane receptors.

            The concept of biased agonism has recently come to the fore with the realization that seven-transmembrane receptors (7TMRs, also known as G protein-coupled receptors, or GPCRs) activate complex signaling networks and can adopt multiple active conformations upon agonist binding. As a consequence, the "efficacy" of receptors, which was classically considered linear, is now recognized as pluridimensional. Biased agonists selectively stabilize only a subset of receptor conformations induced by the natural "unbiased" ligand, thus preferentially activating certain signaling mechanisms. Such agonists thus reveal the intriguing possibility that one can direct cellular signaling with unprecedented precision and specificity and support the notion that biased agonists may identify new classes of therapeutic agents that have fewer side effects. This review focuses on one particular class of biased ligands that has the ability to alter the balance between G protein-dependent and β-arrestin-dependent signal transduction.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              G protein-coupled receptor allosterism and complexing.

              G protein-coupled receptors (GPCRs) represent the largest family of cell-surface receptors. These receptors are natural allosteric proteins because agonist-mediated signaling by GPCRs requires a conformational change in the receptor protein transmitted between two topographically distinct binding sites, one for the agonist and another for the G protein. It is now becoming increasingly recognized, however, that the agonist-bound GPCR can also form ternary complexes with other ligands or "accessory" proteins and display altered binding and/or signaling properties in relation to the binary agonist-receptor complex. Allosteric sites on GPCRs represent novel drug targets because allosteric modulators possess a number of theoretical advantages over classic orthosteric ligands, such as a ceiling level to the allosteric effect and a potential for greater GPCR subtype-selectivity. Because of the noncompetitive nature of allosteric phenomena, the detection and quantification of such effects often relies on a combination of equilibrium binding, nonequilibrium kinetic, and functional signaling assays. This review discusses the development and properties of allosteric receptor models for GPCRs and the detection and quantification of allosteric effects. Moreover, we provide an overview of the current knowledge regarding the location of possible allosteric sites on GPCRs and candidate endogenous allosteric modulators. Finally, we discuss the potential for allosteric effects arising from the formation of GPCR oligomers or GPCRs complexed with accessory cellular proteins. It is proposed that the study of allosteric phenomena will become of progressively greater import to the drug discovery process due to the advent of newer and more sensitive GPCR screening technologies.
                Bookmark

                Author and article information

                Journal
                J Med Chem
                J. Med. Chem
                jm
                jmcmar
                Journal of Medicinal Chemistry
                American Chemical Society
                0022-2623
                1520-4804
                30 June 2015
                30 June 2014
                14 August 2014
                : 57
                : 15
                : 6383-6392
                Affiliations
                []Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota , WDH 8-114, 308 Harvard Street SE, Minneapolis, Minnesota 55455, United States
                [2] Department of Neuroscience and §NINDS Mouse Behavioral Phenotyping Core, University of Minnesota , Minneapolis, Minnesota 55455, United States
                Author notes
                [* ]Phone: (612)-624-9174. Fax: (202)-513-8609. E-mail: porto001@ 123456umn. edu .
                Article
                10.1021/jm500159d
                4136663
                24978316
                5d5a3b19-7c30-4d3f-953e-cbd37bfc1b56
                Copyright © 2014 American Chemical Society

                Terms of Use

                History
                : 29 January 2014
                Funding
                National Institutes of Health, United States
                Categories
                Article
                Custom metadata
                jm500159d
                jm-2014-00159d

                Pharmaceutical chemistry
                Pharmaceutical chemistry

                Comments

                Comment on this article