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McKinstry-Wu AR, Woll KA, Joseph TT, Bu W, White ER, Bhanu NV, Garcia BA, Brannigan G, Dailey WP, Eckenhoff RG. Azi-medetomidine: Synthesis and Characterization of a Novel α2 Adrenergic Photoaffinity Ligand. ACS Chem Neurosci 2019; 10:4716-4728. [PMID: 31638765 DOI: 10.1021/acschemneuro.9b00484] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Agonists at the α2 adrenergic receptor produce sedation, increase focus, provide analgesia, and induce centrally mediated hypotension and bradycardia, yet neither their dynamic interactions with adrenergic receptors nor their modulation of neuronal circuit activity is completely understood. Photoaffinity ligands of α2 adrenergic agonists have the potential both to capture discrete moments of ligand-receptor interactions and to prolong naturalistic drug effects in discrete regions of tissue in vivo. We present here the synthesis and characterization of a novel α2 adrenergic agonist photolabel based on the imidazole medetomidine called azi-medetomidine. Azi-medetomidine shares protein association characteristics with its parent compound in experimental model systems and by molecular dynamics simulation of interactions with the α2A adrenergic receptor. Azi-medetomidine acts as an agonist at α2A adrenergic receptors, and produces hypnosis in Xenopus laevis tadpoles. Azi-medetomidine competes with the α2 agonist clonidine at α2A adrenergic receptors, which is potentiated by photolabeling, and azi-medetomidine labels moieties on the α2A adrenergic receptor as determined by mass spectrometry in a manner consistent with a simulated model. This novel α2 adrenergic agonist photolabel can serve as a powerful tool for in vitro and in vivo investigations of adrenergic signaling.
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Affiliation(s)
- Andrew R. McKinstry-Wu
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - Kellie A. Woll
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - Thomas T. Joseph
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - Weiming Bu
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - E. Railey White
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - Natarajan V. Bhanu
- Epigenetics Institute, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Benjamin A. Garcia
- Epigenetics Institute, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Grace Brannigan
- Center for Computational and Integrative Biology, Department of Physics, Rutgers University, Camden, New Jersey 08102, United States
| | - William P. Dailey
- Department of Chemistry, University of Pennsylvania School of Arts and Sciences, 231 S. 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Roderic G. Eckenhoff
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
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2
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Therapeutic Effect of Agmatine on Neurological Disease: Focus on Ion Channels and Receptors. Neurochem Res 2019; 44:735-750. [PMID: 30610652 DOI: 10.1007/s11064-018-02712-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/19/2018] [Accepted: 12/24/2018] [Indexed: 02/08/2023]
Abstract
The central nervous system (CNS) is the most injury-prone part of the mammalian body. Any acute or chronic, central or peripheral neurological disorder is related to abnormal biochemical and electrical signals in the brain cells. As a result, ion channels and receptors that are abundant in the nervous system and control the electrical and biochemical environment of the CNS play a vital role in neurological disease. The N-methyl-D-aspartate receptor, 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl) propanoic acid receptor, kainate receptor, acetylcholine receptor, serotonin receptor, α2-adrenoreceptor, and acid-sensing ion channels are among the major channels and receptors known to be key components of pathophysiological events in the CNS. The primary amine agmatine, a neuromodulator synthesized in the brain by decarboxylation of L-arginine, can regulate ion channel cascades and receptors that are related to the major CNS disorders. In our previous studies, we established that agmatine was related to the regulation of cell differentiation, nitric oxide synthesis, and murine brain endothelial cell migration, relief of chronic pain, cerebral edema, and apoptotic cell death in experimental CNS disorders. In this review, we will focus on the pathophysiological aspects of the neurological disorders regulated by these ion channels and receptors, and their interaction with agmatine in CNS injury.
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Vass M, Podlewska S, de Esch IJP, Bojarski AJ, Leurs R, Kooistra AJ, de Graaf C. Aminergic GPCR-Ligand Interactions: A Chemical and Structural Map of Receptor Mutation Data. J Med Chem 2018; 62:3784-3839. [PMID: 30351004 DOI: 10.1021/acs.jmedchem.8b00836] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The aminergic family of G protein-coupled receptors (GPCRs) plays an important role in various diseases and represents a major drug discovery target class. Structure determination of all major aminergic subfamilies has enabled structure-based ligand design for these receptors. Site-directed mutagenesis data provides an invaluable complementary source of information for elucidating the structural determinants of binding of different ligand chemotypes. The current study provides a comparative analysis of 6692 mutation data points on 34 aminergic GPCR subtypes, covering the chemical space of 540 unique ligands from mutagenesis experiments and information from experimentally determined structures of 52 distinct aminergic receptor-ligand complexes. The integrated analysis enables detailed investigation of structural receptor-ligand interactions and assessment of the transferability of combined binding mode and mutation data across ligand chemotypes and receptor subtypes. An overview is provided of the possibilities and limitations of using mutation data to guide the design of novel aminergic receptor ligands.
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Affiliation(s)
- Márton Vass
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands
| | - Sabina Podlewska
- Department of Medicinal Chemistry, Institute of Pharmacology , Polish Academy of Sciences , Smętna 12 , PL31-343 Kraków , Poland
| | - Iwan J P de Esch
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands
| | - Andrzej J Bojarski
- Department of Medicinal Chemistry, Institute of Pharmacology , Polish Academy of Sciences , Smętna 12 , PL31-343 Kraków , Poland
| | - Rob Leurs
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands
| | - Albert J Kooistra
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands.,Department of Drug Design and Pharmacology , University of Copenhagen , Universitetsparken 2 , 2100 Copenhagen , Denmark
| | - Chris de Graaf
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands.,Sosei Heptares , Steinmetz Building, Granta Park, Great Abington , Cambridge CB21 6DG , U.K
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4
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Schann S, Greney H, Gasparik V, Dontenwill M, Rascente C, Lacroix G, Monassier L, Bruban V, Feldman J, Ehrhardt JD, Bousquet P. Methylation of imidazoline related compounds leads to loss of α2-adrenoceptor affinity. Synthesis and biological evaluation of selective I1 imidazoline receptor ligands. Bioorg Med Chem 2012; 20:4710-5. [DOI: 10.1016/j.bmc.2012.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/28/2012] [Accepted: 06/02/2012] [Indexed: 10/28/2022]
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5
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Fanelli F, De Benedetti PG. Update 1 of: computational modeling approaches to structure-function analysis of G protein-coupled receptors. Chem Rev 2011; 111:PR438-535. [PMID: 22165845 DOI: 10.1021/cr100437t] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41125 Modena, Italy.
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Abstract
G protein-coupled receptors (GPCRs) comprise a large class of transmembrane proteins that play critical roles in both normal physiology and pathophysiology. These critical roles offer targets for therapeutic intervention, as exemplified by the substantial fraction of current pharmaceutical agents that target members of this family. Tremendous contributions to our understanding of GPCR structure and dynamics have come from both indirect and direct structural characterization techniques. Key features of GPCR conformations derived from both types of characterization techniques are reviewed.
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Affiliation(s)
- Abby L. Parrill
- Department of Chemistry, The University of Memphis, Memphis, TN 38152, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-901-678-2638; Fax: +1-901-678-3447
| | - Debra L. Bautista
- Christian Brothers High School, 5900 Walnut Grove Road, Memphis, TN 38120, USA; E-Mail: (D.L.B.)
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7
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Alachkar A, Brotchie JM, Jones OT. Binding of dopamine and 3-methoxytyramine as l-DOPA metabolites to human alpha(2)-adrenergic and dopaminergic receptors. Neurosci Res 2010; 67:245-9. [PMID: 20302892 DOI: 10.1016/j.neures.2010.03.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 03/11/2010] [Accepted: 03/12/2010] [Indexed: 11/28/2022]
Abstract
The ability of l-3,4-dihydroxyphenylalanine (l-DOPA), l-DOPA-methyl ester and their major metabolites, dopamine, dihydroxyphenylacetic acid (DOPAC), homovanillic (HVA), 3-O-methyldopa and 3-methoxytyramine (3-MT) to bind to alpha(2) adrenergic and D1 and D2 dopamine receptors was assessed by radioligand binding to cloned human receptors expressed in cell lines. As anticipated, dopamine bound with high affinity to D1 (IC(50) 1.1 + or - 0.16 microM) and D2 (IC(50) 0.7 + or - 0.3 microM) dopamine receptors. However, dopamine also bound with high affinity to alpha(2A) (IC(50) was 2.6 + or - 0.5 microM), alpha(2C) (IC(50) 3.2 + or - 0.7 microM). 3-MT bound to alpha(2A) with high affinity (IC(50), 3.6 + or - 0.2 microM) though moderate affinity to alpha(2)c, D1 and D2 receptors (values of IC(50) were 55 + or - 14, 121 + or - 43, 36 + or - 14 microM, respectively). l-DOPA-methyl ester bound with high affinity to alpha(2) (IC(50) 17-36 microM) but not dopamine receptors (IC(50) 0.9-2.5 mM). l-DOPA, 3-O-methyldopa and DOPAC had no observable effect on binding to any of the receptors tested. These data suggest that the effects of l-DOPA in Parkinson's disease may result from actions of its metabolites dopamine and 3-MT on both dopaminergic and non-dopaminergic receptors. These findings may provide explanations for the differences between l-DOPA and dopamine receptor agonists in mediating anti-parkinsonian effects and propensity to be associated with dyskinesia and motor complications such as wearing-off and on-off.
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Affiliation(s)
- Amal Alachkar
- Division of Neuroscience, School of Biological Sciences, University of Manchester, Manchester M13 9PT, UK.
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8
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Shchegolev BF, Shlyakhto EV, Khrustaleva RS, Katina IE, Tsyrlin VA. The role of stacking interactions in clonidine binding. Biophysics (Nagoya-shi) 2008. [DOI: 10.1134/s0006350907060024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Laurila JMM, Xhaard H, Ruuskanen JO, Rantanen MJM, Karlsson HK, Johnson MS, Scheinin M. The second extracellular loop of alpha2A-adrenoceptors contributes to the binding of yohimbine analogues. Br J Pharmacol 2007; 151:1293-304. [PMID: 17558432 PMCID: PMC2189838 DOI: 10.1038/sj.bjp.0707330] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE Rodent alpha(2A)-adrenoceptors bind the classical alpha(2)-antagonists yohimbine and rauwolscine with lower affinity than the human alpha(2A)-adrenoceptor. A serine-cysteine difference in the fifth transmembrane helix (TM; position 5.43) partially explains this, but all determinants of the interspecies binding selectivity are not known. Molecular models of alpha(2A)-adrenoceptors suggest that the second extracellular loop (XL2) folds above the binding cavity and may participate in antagonist binding. EXPERIMENTAL APPROACH Amino acids facing the binding cavity were identified using molecular models: side chains of residues 5.43 in TM5 and xl2.49 and xl2.51 in XL2 differ between the mouse and human receptors. Reciprocal mutations were made in mouse and human alpha(2A)-adrenoceptors at positions 5.43, xl2.49 and xl2.51, and tested with a set of thirteen chemically diverse ligands in competition binding assays. KEY RESULTS Reciprocal effects on the binding of yohimbine and rauwolscine in human and mouse alpha(2A)-adrenoceptors were observed for mutations at 5.43, xl2.49 and xl2.51. The binding profile of RS-79948-197 was reversed only by the XL2 substitutions. CONCLUSIONS AND IMPLICATIONS Positions 5.43, xl2.49 and xl2.51 are major determinants of the species preference for yohimbine and rauwolscine of the human versus mouse alpha(2A)-adrenoceptors. Residues at positions xl2.49 and xl2.51 determine the binding preference of RS-79948-197 for the human alpha(2A)-adrenoceptor. Thus, XL2 is involved in determining the species preferences of alpha(2A)-adrenoceptors of human and mouse for some antagonists.
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Affiliation(s)
- J M M Laurila
- Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Itäinen Pitkäkatu 4B, FL-20520 Turku, Finland.
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10
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Grunewald GL, Seim MR, Lu J, Makboul M, Criscione KR. Application of the Goldilocks effect to the design of potent and selective inhibitors of phenylethanolamine N-methyltransferase: balancing pKa and steric effects in the optimization of 3-methyl-1,2,3,4-tetrahydroisoquinoline inhibitors by beta-fluorination. J Med Chem 2006; 49:2939-52. [PMID: 16686536 PMCID: PMC2770873 DOI: 10.1021/jm051262k] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
3-Methyl-1,2,3,4-tetrahydroisoquinolines (3-methyl-THIQs) are potent inhibitors of phenylethanolamine N-methyltransferase (PNMT), but are not selective due to significant affinity for the alpha(2)-adrenoceptor. Fluorination of the methyl group lowers the pK(a) of the THIQ amine from 9.53 (CH(3)) to 7.88 (CH(2)F), 6.42 (CHF(2)), and 4.88 (CF(3)). This decrease in pK(a) results in a reduction in affinity for the alpha(2)-adrenoceptor. However, increased fluorination also results in a reduction in PNMT inhibitory potency, apparently due to steric and electrostatic factors. Biochemical evaluation of a series of 3-fluoromethyl-THIQs and 3-trifluoromethyl-THIQs showed that the former were highly potent inhibitors of PNMT, but were often nonselective due to significant affinity for the alpha(2)-adrenoceptor, while the latter were devoid of alpha(2)-adrenoceptor affinity, but also lost potency at PNMT. 3-Difluoromethyl-7-substituted-THIQs have the proper balance of both steric and pK(a) properties and thus have enhanced selectivity versus the corresponding 3-fluoromethyl-7-substituted-THIQs and enhanced PNMT inhibitory potency versus the corresponding 3-trifluoromethyl-7-substituted-THIQs. Using the "Goldilocks Effect" analogy, the 3-fluoromethyl-THIQs are too potent (too hot) at the alpha(2)-adrenoceptor and the 3-trifluoromethyl-THIQs are not potent enough (too cold) at PNMT, but the 3-difluoromethyl-THIQs are just right. They are both potent inhibitors of PNMT and highly selective due to low affinity for the alpha(2)-adrenoceptor. This seems to be the first successful use of the beta-fluorination of aliphatic amines to impart selectivity to a pharmacological agent while maintaining potency at the site of interest.
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Affiliation(s)
- Gary L Grunewald
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
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11
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Fanelli F, De Benedetti PG. Computational Modeling Approaches to Structure−Function Analysis of G Protein-Coupled Receptors. Chem Rev 2005; 105:3297-351. [PMID: 16159154 DOI: 10.1021/cr000095n] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute and Department of Chemistry, University of Modena and Reggio Emilia, via Campi 183, 41100 Modena, Italy.
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12
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Xhaard H, Nyrönen T, Rantanen VV, Ruuskanen JO, Laurila J, Salminen T, Scheinin M, Johnson MS. Model structures of α-2 adrenoceptors in complex with automatically docked antagonist ligands raise the possibility of interactions dissimilar from agonist ligands. J Struct Biol 2005; 150:126-43. [PMID: 15866736 DOI: 10.1016/j.jsb.2004.12.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Revised: 12/20/2004] [Indexed: 11/28/2022]
Abstract
Antagonist binding to alpha-2 adrenoceptors (alpha2-ARs) is not well understood. Structural models were constructed for the three human alpha2-AR subtypes based on the bovine rhodopsin X-ray structure. Twelve antagonist ligands (including covalently binding phenoxybenzamine) were automatically docked to the models. A hallmark of agonist binding is the electrostatic interaction between a positive charge on the agonist and the negatively charged side chain of D3.32. For antagonist binding, ion-pair formation would require deviations of the models from the rhodopsin structural template, e.g., a rotation of TM3 to relocate D3.32 more centrally within the binding cavity, and/or creation of new space near TM2/TM7 such that antagonists would be shifted away from TM5. Thus, except for the quinazolines, antagonist ligands automatically docked to the model structures did not form ion-pairs with D3.32. This binding mode represents a valid alternative, whereby the positive charge on the antagonists is stabilized by cation-pi interactions with aromatic residues (e.g., F6.51) and antagonists interact with D3.32 via carboxylate-aromatic interactions. This binding mode is in good agreement with maps derived from a molecular interaction library that predicts favorable atomic contacts; similar interaction environments are seen for unrelated proteins in complex with ligands sharing similarities with the alpha2-AR antagonists.
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Affiliation(s)
- Henri Xhaard
- Department of Biochemistry and Pharmacy, Abo Akademi University, Tykistökatu 6 A, FIN-20520 Turku, Finland
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13
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Pauwels PJ. Unravelling multiple ligand-activation binding sites using RASSL receptors. Trends Pharmacol Sci 2004; 24:504-7. [PMID: 14559400 DOI: 10.1016/j.tips.2003.08.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
MESH Headings
- Binding Sites
- Humans
- Ligands
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Serotonin, 5-HT4/drug effects
- Receptors, Serotonin, 5-HT4/metabolism
- Signal Transduction
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Affiliation(s)
- Petrus J Pauwels
- Centre d'Immunologie Pierre Fabre 5, Avenue Napoléon III-BP 497, 74164 Saint-Julien-en-Genevois Cedex, France.
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14
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Peltonen JM, Nyrönen T, Wurster S, Pihlavisto M, Hoffrén AM, Marjamäki A, Xhaard H, Kanerva L, Savola JM, Johnson MS, Scheinin M. Molecular mechanisms of ligand-receptor interactions in transmembrane domain V of the alpha2A-adrenoceptor. Br J Pharmacol 2003; 140:347-58. [PMID: 12970108 PMCID: PMC1574035 DOI: 10.1038/sj.bjp.0705439] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. The structural determinants of catechol hydroxyl interactions with adrenergic receptors were examined using 12 alpha2-adrenergic agonists and a panel of mutated human alpha2A-adrenoceptors. The alpha2ASer201 mutant had a Cys --> Ser201 (position 5.43) amino-acid substitution, and alpha2ASer201Cys200 and alpha2ASer201Cys204 had Ser --> Cys200 (5.42) and Ser --> Cys204 (5.46) substitutions, respectively, in addition to the Cys --> Ser201 substitution. 2. Automated docking methods were used to predict the receptor interactions of the ligands. Radioligand-binding assays and functional [35S]GTPgammaS-binding assays were performed using transfected Chinese hamster ovary cells to experimentally corroborate the predicted binding modes. 3. The hydroxyl groups of phenethylamines were found to have different effects on ligand affinity towards the activated and resting forms of the wild-type alpha2A-adrenoceptor. Substitution of Ser200 or Ser204 with cysteine caused a deterioration in the capability of catecholamines to activate the alpha2A-adrenoceptor. The findings indicate that (i) Cys201 plays a significant role in the binding of catecholamine ligands and UK14,304 (for the latter, by a hydrophobic interaction), but Cys201 is not essential for receptor activation; (ii) Ser200 interacts with the meta-hydroxyl group of phenethylamine ligands, affecting both catecholamine binding and receptor activation; while (iii) substituting Ser204 with a cysteine interferes both with the binding of catecholamine ligands and with receptor activation, due to an interaction between Ser204 and the para-hydroxyl group of the catecholic ring.
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MESH Headings
- Adrenergic Agonists/metabolism
- Adrenergic Agonists/pharmacology
- Amino Acid Sequence
- Amino Acid Substitution
- Animals
- Binding Sites/genetics
- Binding, Competitive/drug effects
- Brimonidine Tartrate
- CHO Cells
- Catecholamines/chemistry
- Catecholamines/metabolism
- Cricetinae
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Idazoxan/analogs & derivatives
- Idazoxan/metabolism
- Ligands
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Models, Molecular
- Molecular Structure
- Mutation
- Protein Structure, Tertiary
- Quinoxalines/chemistry
- Quinoxalines/metabolism
- Radioligand Assay
- Receptors, Adrenergic, alpha-2/chemistry
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Sequence Homology, Amino Acid
- Sulfur Radioisotopes
- Tritium
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Affiliation(s)
- Juha M Peltonen
- Department of Pharmacology and Clinical Pharmacology, University of Turku, Finland
- Turku Graduate School of Biomedical Sciences, University of Turku, Finland
| | - Tommi Nyrönen
- Department of Biochemistry and Pharmacy, Åbo Akademi University, Turku, Finland
- Center for Scientific Computing, Espoo
| | | | - Marjo Pihlavisto
- Department of Pharmacology and Clinical Pharmacology, University of Turku, Finland
| | | | - Anne Marjamäki
- Department of Pharmacology and Clinical Pharmacology, University of Turku, Finland
| | - Henri Xhaard
- Department of Biochemistry and Pharmacy, Åbo Akademi University, Turku, Finland
| | - Liisa Kanerva
- Departments of Chemistry and Biomedicine, University of Turku, Turku, Finland
| | | | - Mark S Johnson
- Department of Biochemistry and Pharmacy, Åbo Akademi University, Turku, Finland
| | - Mika Scheinin
- Department of Pharmacology and Clinical Pharmacology, University of Turku, Finland
- Author for correspondence:
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15
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Pauwels PJ, Rauly I, Wurch T. Dissimilar pharmacological responses by a new series of imidazoline derivatives at precoupled and ligand-activated alpha 2A-adrenoceptor states: evidence for effector pathway-dependent differential antagonism. J Pharmacol Exp Ther 2003; 305:1015-23. [PMID: 12649300 DOI: 10.1124/jpet.102.048215] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Whereas agonist-directed differential signaling at a single receptor subtype has become an accepted pharmacological concept, distinct behaviors by ligands that are assumed to be antagonists is less documented. The intrinsic activity and capacity of antagonism for a new series of imidazoline-derived adrenergic ligands analogous to dexefaroxan were investigated by measuring two distinct signaling pathways at the recombinant human alpha 2A-adrenoceptor (alpha 2A AR): 1) pertussis toxin-resistant guanosine 5'-O-(3-[35S]thio)triphosphate ([35S]GTP gamma S) binding responses mediated by either a recombinant G alpha oCys351Ile or G alpha i2Cys352Ile protein in CHO-K1 cells, and 2) inhibition of cAMP formation in a stably transfected C6-glial cell line. Ligands could be differentiated as inverse agonists [i.e., 2-(4-methoxy-2-ethyl-2,3-dihydrobenzofuran-2-yl)-4,5-dihydro-1H-imidazole; RX 851062], neutral antagonists [i.e., 2-(4-hydroxy-2-ethyl-2,3-dihydrobenzofuran-2-yl)-4,5-dihydro-1H-imidazole; RX 851057], partial [i.e., 2-(4-chloro-2,3-dihydrobenzofuran-2-yl)-4,5-dihydro-1H-imidazole; RX 821008], and high-efficacy [i.e., 2-(6,7-dichloro-2,3-dihydrobenzofuran-2-yl)-4,5-dihydro-1H-imidazole; RX 821010] agonists at a precoupled alpha 2A AR state in the copresence of a G alpha oCys351Ile protein but not G alpha i2Cys352Ile protein by monitoring [35S]GTP gamma S binding responses. Neither positive nor negative efficacy was observed for these compounds by monitoring the adenylate cyclase pathway at a presumably low-affinity alpha 2A AR state. The capacity of the dexefaroxan analogs to antagonize the (-)-epinephrine-mediated [35S]GTP gamma S binding response at a G alpha oCys351Ile protein was inversely correlated with their magnitude of intrinsic activity and unrelated to their ligand binding affinity for the alpha 2A AR. On the other hand, their capacity to antagonize either (-)-epinephrine or 5-bromo-6-(2-imidazolin-2-ylamino)quinoxaline tartrate (UK 14304)-mediated inhibition of forskolin-stimulated cAMP formation was not related with the rank order of antagonist capacity for the (-)-epinephrine-mediated [35S]GTP gamma S binding response. In conclusion, these data demonstrate that certain alpha2 AR ligands that are assumed to be antagonists, may yield dissimilar pharmacological responses, dependent on the investigated agonist-stimulated effector pathway.
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Affiliation(s)
- Petrus J Pauwels
- Department of Cellular and Molecular Biology, Centre de Recherche Pierre Fabre, 17, avenue Jean Moulin, 81106 Castres Cédex, France.
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16
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Affiliation(s)
- P Häyry
- Transplantation Laboratory, The Haartman Institute, Helsinki, Finland
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17
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Frang H, Cockcroft V, Karskela T, Scheinin M, Marjamäki A. Phenoxybenzamine binding reveals the helical orientation of the third transmembrane domain of adrenergic receptors. J Biol Chem 2001; 276:31279-84. [PMID: 11395517 DOI: 10.1074/jbc.m104167200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phenoxybenzamine (PB), a classical alpha-adrenergic antagonist, binds irreversibly to the alpha-adrenergic receptors (ARs). Amino acid sequence alignments and the predicted helical arrangement of the seven transmembrane (TM) domains suggested an accessible cysteine residue in transmembrane 3 of the alpha(2)-ARs, in position C(3.36) (in subtypes A, B, and C corresponding to amino acid residue numbers 117/96/135, respectively), as a possible site for the PB interaction. Irreversible binding of PB to recombinant human alpha(2)-ARs (90 nm, 30 min) reduced the ligand binding capacity of alpha(2A)-, alpha(2B)-, and alpha(2C)-AR by 81, 96, and 77%. When the TM3 cysteine, Cys(117), of alpha(2A)-AR was mutated to valine (alpha(2A)-C117V), the receptor became resistant to PB (inactivation, 10%). The beta(2)-AR contains a valine in this position (V(3.36); position number 117) and a cysteine in the preceding position (Cys(116)) and was not inactivated by PB (10 microm, 30 min) (inactivation 26%). The helical orientation of TM3 was tested by exchanging the amino acids at positions 116 and 117 of the alpha(2A)-AR and beta(2)-AR. The alpha(2A)-F116C/C117V mutant was resistant to PB (inactivation, 7%), whereas beta(2)-V117C was irreversibly inactivated (inactivation, 93%), confirming that position 3.36 is exposed to receptor ligands, and position 3.35 is not exposed in the binding pocket.
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Affiliation(s)
- H Frang
- Department of Pharmacology, University of Turku, FIN-20520 Turku and Orion Pharma, FIN-20101 Turku, Finland
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18
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Nyrönen T, Pihlavisto M, Peltonen JM, Hoffrén AM, Varis M, Salminen T, Wurster S, Marjamäki A, Kanerva L, Katainen E, Laaksonen L, Savola JM, Scheinin M, Johnson MS. Molecular mechanism for agonist-promoted alpha(2A)-adrenoceptor activation by norepinephrine and epinephrine. Mol Pharmacol 2001; 59:1343-54. [PMID: 11306720 DOI: 10.1124/mol.59.5.1343] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We present a mechanism for agonist-promoted alpha(2A)-adrenergic receptor (alpha(2A)-AR) activation based on structural, pharmacological, and theoretical evidence of the interactions between phenethylamine ligands and alpha(2A)-AR. In this study, we have: 1) isolated enantiomerically pure phenethylamines that differ both in their chirality about the beta-carbon, and in the presence/absence of one or more hydroxyl groups: the beta-OH and the catecholic meta- and para-OH groups; 2) used [(3)H]UK-14,304 [5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine; agonist] and [(3)H]RX821002 [2-(2-methoxy-1,4-benzodioxan-2-yl)-2-imidazoline; antagonist] competition binding assays to determine binding affinities of these ligands to the high- and low-affinity forms of alpha(2A)-AR; 3) tested the ability of the ligands to promote receptor activation by measuring agonist-induced stimulation of [(35)S]GTPgammaS binding in isolated cell membranes; and 4) used automated docking methods and our alpha(2A)-AR model to predict the binding modes of the ligands inside the alpha(2A)-AR binding site. The ligand molecules are sequentially missing different functional groups, and we have correlated the structural features of the ligands and ligand-receptor interactions with experimental ligand binding and receptor activation data. Based on the analysis, we show that structural rearrangements in transmembrane helix (TM) 5 could take place upon binding and subsequent activation of alpha(2A)-AR by phenethylamine agonists. We suggest that the following residues are important in phenethylamine interactions with alpha(2A)-AR: Asp113 (D(3.32)), Val114 (V(3.33)), and Thr118 (T(3.37)) in TM3; Ser200 (S(5.42)), Cys201 (C(5.43)), and Ser204 (S(5.46)) in TM5; Phe391 (F(6.52)) and Tyr394 (Y(6.55)) in TM6; and Phe411 (F(7.38)) and Phe412 (F(7.39)) in TM7.
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Affiliation(s)
- T Nyrönen
- Department of Biochemistry and Pharmacy, Abo Akademi University, Turku, Finland
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19
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Assil IQ, Qi LJ, Arai M, Shomali M, Abou-Samra AB. Juxtamembrane region of the amino terminus of the corticotropin releasing factor receptor type 1 is important for ligand interaction. Biochemistry 2001; 40:1187-95. [PMID: 11170443 DOI: 10.1021/bi001758y] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The functional properties of the amino terminus (NT) of the corticotropin releasing factor (CRF) receptor type 1 (R1) were studied by use of murine (m) CRFR1 and rat (r) parathyroid hormone (PTH)/parathyroid hormone-related peptide receptor (PTH1R) chimeras. The chimeric receptor CXP, in which the NT of mCRFR1 was annealed to the TMs of PTH1R, and the reciprocal hybrid, PXC, bound radiolabeled analogues of sauvagine and PTH(3--34), respectively. Neither hybrid bound radiolabeled CRF or PTH(1--34). CRF and PTH(1--34) weakly stimulated intracellular cAMP accumulation in COS-7 cells transfected with PXC and CXP, respectively. Thus the NT is required for ligand binding and the TMs are required for agonist-stimulated cAMP accumulation. Replacing individual intercysteine segments of PXC with their mCRFR1 counterparts did not rescue CRF or sauvagine radioligand binding or stimulation of cAMP accumulation. Replacement of residues 1--31 of mCRFR1 with their PTH1R counterparts resulted in a chimeric receptor, PEC, which had normal CRFR1 functional properties. In addition, a series of chimeras (F1PEC--F6PEC) were generated by replacement of the NT intercysteine residues of PEC with their PTH1R counterparts. Only F1PEC, F2PEC, and F3PEC showed detectable CRF and sauvagine radioligand binding. All of the PEC chimeras except F5PEC increased cAMP accumulation. These data indicate that the Cys(68)(-)Glu(109) domain is important for binding and that the Cys(87)(-)Cys(102) region plays an important role in CRFR1 activation.
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MESH Headings
- Amino Acid Sequence
- Amphibian Proteins
- Animals
- COS Cells
- Cyclic AMP/metabolism
- Ligands
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Membrane Proteins/physiology
- Mice
- Mice, Inbred BALB C
- Molecular Sequence Data
- Mutagenesis, Insertional
- Peptide Fragments/chemistry
- Peptide Fragments/genetics
- Peptide Fragments/metabolism
- Peptide Fragments/physiology
- Peptide Hormones
- Peptides/pharmacology
- Protein Structure, Tertiary/genetics
- Proto-Oncogene Proteins c-myc/genetics
- Rats
- Receptor, Parathyroid Hormone, Type 1
- Receptors, Corticotropin-Releasing Hormone/chemistry
- Receptors, Corticotropin-Releasing Hormone/genetics
- Receptors, Corticotropin-Releasing Hormone/metabolism
- Receptors, Corticotropin-Releasing Hormone/physiology
- Receptors, Parathyroid Hormone/chemistry
- Receptors, Parathyroid Hormone/genetics
- Receptors, Parathyroid Hormone/metabolism
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/metabolism
- Structure-Activity Relationship
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Affiliation(s)
- I Q Assil
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
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20
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Metzler DE, Metzler CM, Sauke DJ. Chemical Communication Between Cells. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50033-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Molderings GJ, Bönisch H, Brüss M, Likungu J, Göthert M. Species-specific pharmacological properties of human alpha(2A)-adrenoceptors. Hypertension 2000; 36:405-10. [PMID: 10988273 DOI: 10.1161/01.hyp.36.3.405] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
On the basis of data obtained in rabbits, the imidazoline receptor ligand rilmenidine has been suggested to decrease blood pressure in humans by activating central alpha(2A)-adrenoceptors. A prerequisite for this hypothesis was the unproved assumption that rabbit and human alpha(2A)-adrenoceptors are equally activated by rilmenidine. Because alpha(2A)-adrenoceptors in the brain and on cardiovascular sympathetic nerve terminals are identical, the latter were used as a model for the former to confirm or disprove this assumption. Human atrial appendages and rabbit pulmonary arteries were used to determine the potencies of alpha(2)-adrenoceptor agonists in inhibiting the electrically (2 Hz) evoked [(3)H]norepinephrine release and of antagonists in counteracting the alpha(2)-adrenoceptor-mediated inhibition induced by moxonidine. In the rabbit pulmonary artery, rilmenidine and oxymetazoline are potent full agonists, whereas in the human atrial appendages they are antagonists at the alpha(2)-autoreceptors, sharing this property with rauwolscine, phentolamine, and idazoxan. In contrast, prazosin is ineffective. In addition, a partial nucleotide and amino acid sequence of the rabbit alpha(2A)-adrenoceptor (a region known to substantially influence the pharmacological characteristics of the alpha(2)-adrenoceptor) revealed marked differences between the rabbit and the human alpha(2A)-adrenoceptor. The sympathetic nerves of both the human atrial appendages and rabbit pulmonary artery are endowed with alpha(2A)-autoreceptors, at which, however, both rilmenidine and oxymetazoline exhibit different properties (antagonism and agonism, respectively). The antagonistic property of rilmenidine at human alpha(2A)-adrenoceptors indicates that in contrast to the suggestion based on rabbit data, the hypotensive property of the drug in humans is not due to activation of alpha(2A)-adrenoceptors but other, presumably I(1)-imidazoline receptors, are probably involved.
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Affiliation(s)
- G J Molderings
- Institut für Pharmakologie und Toxikologie, Universität Bonn, Bonn, Germany.
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22
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Scheinin M, Pihlavisto M. Molecular pharmacology of alpha2-adrenoceptor agonists. Best Pract Res Clin Anaesthesiol 2000. [DOI: 10.1053/bean.2000.0080] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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