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Ashton AW. Preparing to strike: Acute events in signaling by the serpentine receptor for thromboxane A 2. Pharmacol Ther 2023:108478. [PMID: 37321373 DOI: 10.1016/j.pharmthera.2023.108478] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/31/2023] [Accepted: 06/07/2023] [Indexed: 06/17/2023]
Abstract
Over the last two decades, awareness of the (patho)physiological roles of thromboxane A2 signaling has been greatly extended. From humble beginnings as a short-lived stimulus that activates platelets and causes vasoconstriction to a dichotomous receptor system involving multiple endogenous ligands capable of modifying tissue homeostasis and disease generation in almost every tissue of the body. Thromboxane A2 receptor (TP) signal transduction is associated with the pathogenesis of cancer, atherosclerosis, heart disease, asthma, and host response to parasitic infection amongst others. The two receptors mediating these cellular responses (TPα and TPβ) are derived from a single gene (TBXA2R) through alternative splicing. Recently, knowledge about the mechanism(s) of signal propagation by the two receptors has undergone a revolution in understanding. Not only have the structural relationships associated with G-protein coupling been established but the modulation of that signaling by post-translational modification to the receptor has come sharply into focus. Moreover, the signaling of the receptor unrelated to G-protein coupling has become a burgeoning field of endeavor with over 70 interacting proteins currently identified. These data are reshaping the concept of TP signaling from a mere guanine nucleotide exchange factors for Gα activation to a nexus for the convergence of diverse and poorly characterized signaling pathways. This review summarizes the advances in understanding in TP signaling, and the potential for new growth in a field that after almost 50 years is finally coming of age.
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Affiliation(s)
- Anthony W Ashton
- Division of Cardiovascular Medicine, Lankenau Institute for Medical Research, Rm 128, 100 E Lancaster Ave, Wynnewood, PA 19096, USA; Division of Perinatal Research, Kolling Institute of Medical Research, Faculty of Medicine and Health, University of Sydney, St Leonards, NSW 2065, Australia.
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2
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Hoxha M, Buccellati C, Capra V, Garella D, Cena C, Rolando B, Fruttero R, Carnevali S, Sala A, Rovati G, Bertinaria M. In vitro pharmacological evaluation of multitarget agents for thromboxane prostanoid receptor antagonism and COX-2 inhibition. Pharmacol Res 2016; 103:132-43. [DOI: 10.1016/j.phrs.2015.11.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 11/15/2015] [Indexed: 11/29/2022]
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3
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Wang X, Liu L, Huang L, Herbst-Robinson K, Cornec AS, James MJ, Sugiyama S, Bassetto M, Brancale A, Trojanowski JQ, Lee VMY, Smith AB, Brunden KR, Ballatore C. Potent, long-acting cyclopentane-1,3-Dione thromboxane (A2)-receptor antagonists. ACS Med Chem Lett 2014; 5:1015-20. [PMID: 25221659 DOI: 10.1021/ml5002085] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 07/17/2014] [Indexed: 11/29/2022] Open
Abstract
A series of derivatives of the known thromboxane A2 prostanoid (TP) receptor antagonists, 3-(6-((4-chlorophenyl)sulfonamido)-5,6,7,8-tetrahydronaphthalen-1-yl)propanoic acid and 3-(3-(2-((4-chlorophenyl)sulfonamido)ethyl)phenyl) propanoic acid, were synthesized in which the carboxylic acid functional group was replaced with substituted cyclopentane-1,3-dione (CPD) bioisosteres. Characterization of these molecules led to the discovery of remarkably potent new analogues, some of which were considerably more active than the corresponding parent carboxylic acid compounds. Depending on the choice of the C2 substituent of the CPD unit, these new derivatives can produce either a reversible or an apparent irreversible inhibition of the human TP receptor. Given the potency and the long-lasting inhibition of TP receptor signaling, these novel antagonists may comprise promising leads for the development of antithromboxane therapies.
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Affiliation(s)
| | | | | | | | | | | | | | - Marcella Bassetto
- School
of Pharmacy and Pharmaceutical Sciences, Cardiff University, King Edward VII Avenue, Cardiff CF10 3NB, United Kingdom
| | - Andrea Brancale
- School
of Pharmacy and Pharmaceutical Sciences, Cardiff University, King Edward VII Avenue, Cardiff CF10 3NB, United Kingdom
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Lu N, Zhan M, Gao C, Wu G, Zhang H. I4, a new synthetic sulfonylurea compound, inhibits the action of TXA2 in vivo and in vitro on platelets and aorta vascular smooth muscle. Thromb Res 2012; 130:e209-15. [DOI: 10.1016/j.thromres.2012.07.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 06/16/2012] [Accepted: 07/24/2012] [Indexed: 11/17/2022]
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6
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Krishna A, Yadav A. Lead compound design for TPR/COX dual inhibition. J Mol Model 2012; 18:4397-408. [PMID: 22588583 DOI: 10.1007/s00894-012-1435-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 04/17/2012] [Indexed: 11/24/2022]
Abstract
The modes of action of TxA2 antagonists and COX-2 inhibitors were studied utilizing flexible ligand docking with postdocking minimization and ab initio interaction energy calculations. The resulting increased understanding of their binding interactions led to the design of a lead compound with chemical moieties that allowed efficient binding to both the thromboxane receptor and the COX-2 enzyme. This compound is derived from allicin, a natural component of garlic, and is a good starting point for the development of anti-inflammatory drugs with fewer side effects or improved cardiovascular drugs.
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Affiliation(s)
- Abhay Krishna
- Department of Chemistry, University Institute of Engineering and Technology, CSJM University, Kanpur, 208024, India.
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7
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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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8
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Mechanisms underlining gender differences in Phenylephrine contraction of normoglycaemic and short-term Streptozotocin-induced diabetic WKY rat aorta. Vascul Pharmacol 2011; 57:81-90. [PMID: 22172524 DOI: 10.1016/j.vph.2011.11.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 09/28/2011] [Accepted: 11/29/2011] [Indexed: 01/30/2023]
Abstract
The female gender reduces the risk, but succumbs more to cardiovascular disease. The hypothesis that short-term (8weeks) Streptozotocin-induced diabetes could produce greater female than male vascular tissue reactivity and the mechanistic basis were explored. Aortic ring responses to Phenylephrine were examined in age- and sex-matched normoglycaemic/diabetic rats. The normoglycaemic male tissue contracted significantly more than the normoglycaemic female and the male/female diabetic tissues. Endothelial-denudation, l-NAME or MB reversed these differences suggesting an EDNO-cGMP dependence. 17β-oestradiol exerted relaxant effect on all endothelium-denuded (and normoglycaemic endothelium-intact male) tissues, but not endothelium-intact normoglycaemic female. The greater male tissue contraction is attributable to absent 17β-oestradiol-modulated relaxation. Indomethacin blockade of COX attenuated male normoglycaemic and female diabetic tissue contraction (both reversed by l-NAME), but augmented diabetic male tissue contraction. These data are consistent with the raised contractile TXA(2) and PGE(2) in normoglycaemic male and diabetic female tissues, and the relaxant PGI(2) in diabetic male (and female). The higher levels of PGI(2) in the normoglycaemic and diabetic female perhaps explain their greater relaxant response to Acetylcholine compared to the respective male. In conclusion, there is an endothelium-dependent gender difference in the effect of short term diabetes on vascular tissue reactivity which is COX mediated.
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9
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Ballatore C, Soper JH, Piscitelli F, James M, Huang L, Atasoylu O, Huryn DM, Trojanowski JQ, Lee VMY, Brunden KR, Smith AB. Cyclopentane-1,3-dione: a novel isostere for the carboxylic acid functional group. Application to the design of potent thromboxane (A2) receptor antagonists. J Med Chem 2011; 54:6969-83. [PMID: 21863799 DOI: 10.1021/jm200980u] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cyclopentane-1,3-diones are known to exhibit pK(a) values typically in the range of carboxylic acids. To explore the potential of the cyclopentane-1,3-dione unit as a carboxylic acid isostere, the physical-chemical properties of representative congeners were examined and compared with similar derivatives bearing carboxylic acid or tetrazole residues. These studies suggest that cyclopentane-1,3-diones may effectively substitute for the carboxylic acid functional group. To demonstrate the use of the cyclopentane-1,3-dione isostere in drug design, derivatives of a known thromboxane A(2) prostanoid (TP) receptor antagonist, 3-(3-(2-(4-chlorophenylsulfonamido)ethyl)phenyl)propanoic acid (12), were synthesized and evaluated in both functional and radioligand-binding assays. A series of mono- and disubstituted cyclopentane-1,3-dione derivatives (41-45) were identified that exhibit nanomolar IC(50) and K(d) values similar to 12. Collectively, these studies demonstrate that the cyclopentane-1,3-dione moiety comprises a novel isostere of the carboxylic acid functional group. Given the combination of the relatively strong acidity, tunable lipophilicity, and versatility of the structure, the cyclopentane-1,3-dione moiety may constitute a valuable addition to the palette of carboxylic acid isosteres.
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Affiliation(s)
- Carlo Ballatore
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States.
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10
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Affiliation(s)
- Takako Hirata
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Shuh Narumiya
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
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11
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Dogné JM, Wouters J, Rolin S, Michaux C, Pochet L, Durant F, Delarge J, Masereel B. Design, synthesis and biological evaluation of a sulfonylcyanoguanidine as thromboxane A2 receptor antagonist and thromboxane synthase inhibitor. J Pharm Pharmacol 2010; 53:669-80. [PMID: 11370706 DOI: 10.1211/0022357011775992] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
The synthesis and the structure of N-isopropyl-N′-[2-(3′-methylphenylamino)-5-nitrobenzenesulfonyl] urea (14) was drawn from two thromboxane A2 receptor antagonists structurally related to torasemide. Compound 14 showed an IC50 value of 22 nm for the thromboxane A2 (TXA2) receptor of human washed platelets. Compound 14 prevented platelet aggregation induced by arachidonic acid (0.6 mm) and U-46619 (1 μm) with an IC50 value of 0.45 and 0.15 μm, respectively. Moreover, 14 relaxed the rat isolated aorta and guinea-pig trachea precontracted by U-46619, a TXA2 agonist. Its efficacy (IC50) was 20.4 and 5.47 nm, respectively. Finally, 14 (1 μm) completely inhibited TXA2 synthase of human platelets. The pKa value and the crystallographic data of 14 were determined and used to propose an interaction model between the TXA2 antagonists related to torasemide and their receptor.
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Affiliation(s)
- J M Dogné
- Department of Pharmacy, University of Namur, Belgium
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12
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Dastmalchi S, Church WB, Morris MB. Modelling the structures of G protein-coupled receptors aided by three-dimensional validation. BMC Bioinformatics 2008; 9 Suppl 1:S14. [PMID: 18315845 PMCID: PMC2259415 DOI: 10.1186/1471-2105-9-s1-s14] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Background G protein-coupled receptors (GPCRs) are abundant, activate complex signalling and represent the targets for up to ~60% of pharmaceuticals but there is a paucity of structural data. Bovine rhodopsin is the first GPCR for which high-resolution structures have been completed but significant variations in structure are likely to exist among the GPCRs. Because of this, considerable effort has been expended on developing in silico tools for refining structures of individual GPCRs. We have developed REPIMPS, a modification of the inverse-folding software Profiles-3D, to assess and predict the rotational orientation and vertical position of helices within the helix bundle of individual GPCRs. We highlight the value of the method by applying it to the Baldwin GPCR template but the method can, in principle, be applied to any low- or high-resolution membrane protein template or structure. Results 3D models were built for transmembrane helical segments of 493 GPCRs based on the Baldwin template, and the models were then scored using REPIMPS and Profiles-3D. The compatibility scores increased significantly using REPIMPS because it takes into account the physicochemical properties of the (lipid) environment surrounding the helix bundle. The arrangement of helices in the helix bundle of the 493 models was then altered systematically by rotating the individual helices. For most GPCRs in the set, changes in the rotational position of one or more helices resulted in significant improvement in the compatibility scores. In particular, for most GPCRs, a rotation of helix VII by 240–300° resulted in improved scores. Bovine rhodopsin modelled using this method showed 3.31 Å RMSD to its crystal structure for 198 Cα atom pairs, suggesting the utility of the method even when starting with idealised structures such as the Baldwin template. Conclusion We have developed an in silico tool which can be used to test the validity of, and refine, models of GPCRs with respect to helix rotation and vertical position based on the physicochemical properties of amino acids and the surrounding environment. The method can be applied to any multi-pass membrane protein and potentially can be used in combination with other high-throughput methodologies to generate and refine models of membrane proteins.
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Affiliation(s)
- Siavoush Dastmalchi
- School of Pharmacy, Tabriz University of Medical Sciences, Tabriz 51664, Iran.
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13
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Ni F, So SP, Cervantes V, Ruan KH. A profile of the residues in the second extracellular loop that are critical for ligand recognition of human prostacyclin receptor. FEBS J 2008; 275:128-37. [PMID: 18042246 PMCID: PMC3046732 DOI: 10.1111/j.1742-4658.2007.06183.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The residues in the second extracellular loop (eLP2) of the prostanoid receptors, which are important for specific ligand recognition, were previously predicted in our earlier studies of the thromboxane A2 receptor (TP) using a combination of NMR spectroscopy and recombinant protein approaches. To further test this hypothesis, another prostanoid receptor, the prostacyclin receptor (IP), which has opposite biological characteristics to that of TP, was used as a model for these studies. A set of recombinant human IPs with site-directed mutations at the nonconserved eLP2 residues were constructed using an Ala-scanning approach, and then expressed in HEK293 and COS-7 cells. The expression levels of the recombinant receptors were six-fold higher in HEK293 cells than in COS-7 cells. The residues important for ligand recognition and binding within the N-terminal segment (G159, Q162, and C165) and the C-terminal segment (L172, R173, M174, and P179) of IP eLP2 were identified by mutagenesis analyses. The molecular mechanisms for the specific ligand recognition of IP were further demonstrated by specific site-directed mutagenesis using different amino acid residues with unique chemical properties for the key residues Q162, L172, R173, and M174. A comparison with the corresponding functional residues identified in TP eLP2 revealed that three (Q162, R173, and M174) of the four residues are nonconserved, and these are proposed to be involved in specific ligand recognition. We discuss the importance of G159 and P179 in ligand recognition through configuration of the loop conformation is discussed. These studies have further indicated that characterization of the residues in the eLP2 regions for all eight prostanoid receptors could be an effective approach for uncovering the molecular mechanisms of the ligand selectivities of the G-protein-coupled receptors.
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Affiliation(s)
- Feng Ni
- The Department of Pharmacological and Pharmaceutical Sciences, and The Center for Experimental Therapeutics and PharmacoInformatics, University of Houston, TX 77204-5037, USA
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14
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Khasawneh FT, Huang JS, Turek JW, Le Breton GC. Differential Mapping of the Amino Acids Mediating Agonist and Antagonist Coordination with the Human Thromboxane A2 Receptor Protein. J Biol Chem 2006; 281:26951-65. [PMID: 16837469 DOI: 10.1074/jbc.m507469200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Despite the well documented involvement of thromboxane A(2) receptor (TPR) signaling in the pathogenesis of thrombotic diseases, there are currently no rationally designed antagonists available for clinical use. To a large extent, this derives from a lack of knowledge regarding the topography of the TPR ligand binding pocket. On this basis, the purpose of the current study was to identify the specific amino acid residues in the TPR protein that regulate ligand coordination and binding. The sites selected for mutation reside within or in close proximity to a region we previously defined as a TPR ligand binding region (i.e. the C terminus of the second extracellular loop and the leading edge of the fifth transmembrane domain). Mutation of these residues caused varying effects on the TPR-ligand coordination process. Specifically, the D193A, D193Q, and D193R mutants lost SQ29,548 (antagonist) binding and exhibited a dramatically reduced calcium response, which could not be restored by elevated U46619 (agonist) doses. The F184Y mutant lost SQ29,548 binding and exhibited a reduced calcium response (which could be restored by elevated U46619); and the T186A and S191T mutants lost SQ29,548 binding and retained a normal U46619-induced calcium response. Furthermore, these last three mutants also revealed a divergence in the binding of two structurally different antagonists, SQ29,548 and BM13.505. Two separate mutants that exhibited SQ29,548 binding yielded either a normal (F196Y) or reduced (S201T) U46619 response. Finally, mutation of other residues directly adjacent to those described above (e.g. E190A and F200A) produced no detectable effects on either SQ29,548 binding or the U46619-induced response. In summary, these results identify key amino acids (in particular Asp(193)) involved in TPR ligand coordination. These findings also demonstrate that TPR-specific ligands interact with different residues in the ligand-binding pocket.
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Affiliation(s)
- Fadi T Khasawneh
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois 60612
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15
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Ruan CH, Wu J, Ruan KH. A strategy using NMR peptide structures of thromboxane A2 receptor as templates to construct ligand-recognition pocket of prostacyclin receptor. BMC BIOCHEMISTRY 2005; 6:23. [PMID: 16271145 PMCID: PMC1298286 DOI: 10.1186/1471-2091-6-23] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Accepted: 11/04/2005] [Indexed: 11/10/2022]
Abstract
Background: Prostacyclin receptor (IP) and thromboxane A2 receptor (TP) belong to rhodopsin-type G protein-coupling receptors and respectively bind to prostacyclin and thromboxane A2 derived from arachidonic acid. Recently, we have determined the extracellular loop (eLP) structures of the human TP receptor by 2-D 1H NMR spectroscopy using constrained peptides mimicking the individual eLP segments. The studies have identified the segment along with several residues in the eLP domains important to ligand recognition, as well as proposed a ligand recognition pocket for the TP receptor. Results: The IP receptor shares a similar primary structure in the eLPs with those of the TP receptor. Forty percent residues in the second eLPs of the receptors are identical, which is the major region involved in forming the ligand recognition pocket in the TP receptor. Based on the high homology score, the eLP domains of the IP receptor were constructed by the homology modeling approach using the NMR structures of the TP eLPs as templates, and then configured to the seven transmembrane (TM) domains model constructed using the crystal structure of the bovine rhodopsin as a template. A NMR structure of iloprost was docked into the modeled IP ligand recognition pocket. After dynamic studies, the segments and residues involved in the IP ligand recognition were proposed. A key residue, Arg173 involved in the ligand recognition for the IP receptor, as predicted from the modeling, was confirmed by site-directed mutagenesis. Conclusion: A 3-D model of the human IP receptor was constructed by homology modeling using the crystal structure of bovine rhodopsin TM domains and the NMR structures of the synthetic constrained peptides of the eLP domains of the TP receptor as templates. This strategy can be applied to molecular modeling and the prediction of ligand recognition pockets for other prostanoid receptors.
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MESH Headings
- Amino Acid Sequence
- Animals
- Binding Sites/physiology
- COS Cells
- Cattle
- Chlorocebus aethiops
- Humans
- Ligands
- Models, Molecular
- Molecular Sequence Data
- Nuclear Magnetic Resonance, Biomolecular/methods
- Receptors, Epoprostenol/chemistry
- Receptors, Epoprostenol/genetics
- Receptors, Epoprostenol/metabolism
- Receptors, Thromboxane A2, Prostaglandin H2/chemistry
- Receptors, Thromboxane A2, Prostaglandin H2/genetics
- Receptors, Thromboxane A2, Prostaglandin H2/metabolism
- Sequence Analysis, Protein/methods
- Templates, Genetic
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Affiliation(s)
- Cheng-Huai Ruan
- From the Vascular Biology Research Center and Division of Hematology, Department of Internal Medicine, The University of Texas Health Science Center, Houston, 6431 Fannin St., Houston, Texas 77030, USA
| | - Jaixin Wu
- From the Vascular Biology Research Center and Division of Hematology, Department of Internal Medicine, The University of Texas Health Science Center, Houston, 6431 Fannin St., Houston, Texas 77030, USA
| | - Ke-He Ruan
- From the Vascular Biology Research Center and Division of Hematology, Department of Internal Medicine, The University of Texas Health Science Center, Houston, 6431 Fannin St., Houston, Texas 77030, USA
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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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17
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Rolin S, Dogne JM, Vastersaegher C, Hanson J, Masereel B. Pharmacological evaluation of both enantiomers of (R,S)-BM-591 as thromboxane A2 receptor antagonists and thromboxane synthase inhibitors. Prostaglandins Other Lipid Mediat 2004; 74:75-86. [PMID: 15560117 DOI: 10.1016/j.prostaglandins.2004.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aim of this work is to evaluate the anti-thromboxane activity of two pure enantiomers of (R,S)-BM-591, a nitrobenzene sulfonylurea chemically related to torasemide, a loop diuretic. The drug affinity for thromboxane A2 receptor (TP) of human washed platelets has been determined. In these experiments, (R)-BM-591 (IC50 = 2.4+/-0.1 nM) exhibited a significant higher affinity than (S)-BM-591 (IC50 = 4.2+/-0.15 nM) for human washed platelets TP receptors. Both enantiomers were stronger ligands than SQ-29548 (IC50 = 21.0+/-1.0 nM) and sulotroban (IC50 = 930+/-42 nM), two reference TXA2 receptor antagonists. Pharmacological characterisations of (S)-BM-591 and (R)-BM-591 were compared in several models. Thus, (R)-BM-591 strongly prevented platelet aggregation induced by arachidonic acid (AA) (600 microM) and U-46619 (1 microM) while (S)-BM-591 showed a lower activity. On isolated tissues pre-contracted by U-46619, a stable TXA2 agonist, (S)-BM-591 was more potent in relaxing guinea-pig trachea (EC50 = 0.272+/-0.054 microM) and rat aorta (EC50 = 0.190+/-0.002 microM) than (R)-BM-591 (EC50 of 9.60+/-0.63 microM and 0.390+/-0.052 microM, respectively). Moreover, at 1 microM, (R)-BM-591 totally inhibited TXA2 synthase activity, expressed as TXB2 production from human platelets, while at the same concentration, (S)-BM-591 poorly reduced the TXB2 synthesis (22%). Finally, in rats, both enantiomers lost the diuretic activity of torasemide. In conclusion, (R)-BM-591 exhibits a higher affinity and antagonism on human platelet TP receptors than (S)-BM-591 as well as a better thromboxane synthase inhibitory potency. In contrast, (S)-BM-591 is more active than the (R)-enantiomer in relaxing smooth muscle contraction of rat aorta and trachea guinea pig. Consequently, (R)-BM-591 represents the best candidate for further development in the field of thrombosis disorders.
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Affiliation(s)
- S Rolin
- Department of Pharmacy, University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
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Hönemann CW, Hahnenkamp K, Podranski T, Strumper D, Hollmann MW, Durieux ME. Local Anesthetics Inhibit Thromboxane A2 Signaling in Xenopus Oocytes and Human K562 Cells. Anesth Analg 2004; 99:930-937. [PMID: 15333434 DOI: 10.1213/01.ane.0000130351.76523.3f] [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] [Indexed: 11/05/2022]
Abstract
Thromboxane A(2) (TXA(2)) has been proposed as a mediator of perioperative myocardial ischemia, vasoconstriction, and thrombosis. As these adverse events are minimized with epidural anesthesia, rather than general anesthesia, we hypothesized that local anesthetics would inhibit TXA(2)-receptor signaling. We used fluorometric determination of intracellular [Ca(2+)] in human K562 cells and 2-electrode voltage clamp measurements in Xenopus laevis oocytes expressing TXA(2) receptors. After 10-min incubation, lidocaine (IC(50): 1.02 +/- 0.2 x 10(-3) M), ropivacaine (IC(50): ropivacaine 6.3 +/- 0.9 x 10(-5) M), or bupivacaine (IC(50): 1.42 +/- 0.08 x 10(-7) M) inhibited TXA(2)-induced [Ca(2+)](i) in K562 cells. These data were confirmed in Xenopus oocytes recombinantly expressing TXA(2) receptors, with IC(50)s of bupivacaine 1.2 +/- 0.2 x 10(-5) M, R(+) ropivacaine 4.9 +/- 1.7 x 10(-4) M, S(-) ropivacaine 5.3 +/- 0.9 x 10(-5) M, and lidocaine 6.4 +/- 2.8 x 10(-4) M. Intracellular pathways activated by IP(3) and GTPgammaS were not significantly affected by the local anesthetics tested. QX314, a positively charged lidocaine analog, inhibited only if injected intracellularly (IC(50): 5.3 +/- 1.7 x 10(-4) M), indicating one local anesthetic target is most likely inside the cell. Benzocaine (largely uncharged) inhibited with an IC(50) of 8.7 +/- 1.8 x 10(-4) M. This suggests that some of the beneficial effects of regional anesthesia techniques might be due to direct interaction of local anesthetics with the functioning of membrane proteins.
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Affiliation(s)
- Christian W Hönemann
- * Klinik und Poliklinik für Anästhesiologie und operative Intensivmedizin, University Hospital, Münster; † Department of Anesthesiology, St. Marienhospital, Vechta; ‡ Department of Anesthesiology, University of Heidelberg, Germany; and § Department of Anesthesiology, University of Virginia, Charlottesville
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Hahnenkamp K, Nollet J, Mper DS, Halene T, Rathman P, Mortier E, Van Aken H, Knapp J, Durieux ME, Hoenemann CW. Bupivacaine Inhibits Thromboxane A2-Induced Vasoconstriction in Rat Thoracic Aorta. Anesth Analg 2004; 99:97-102. [PMID: 15281511 DOI: 10.1213/01.ane.0000118107.62304.25] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Plasma levels of thromboxane A2 (TXA2), an inflammatory mediator inducing platelet aggregation, bronchoconstriction, and vasoconstriction, are increased in the perioperative period. A major role in the pathogenesis of perioperative thromboembolic and ischemic syndromes is attributed to this prostanoid. Local anesthetics (LA) inhibit signaling of TXA2 receptors expressed in cell models. Therefore, we hypothesized that LA may inhibit vasoconstriction induced by the TXA2 analog U46619 in rat thoracic aorta. Rings (3-mm length) of the rat thoracic aorta were mounted in organ baths and isometric contractile force was measured. Rings, with or without endothelium, were incubated for 60 min in bupivacaine (10(-6) or 10(-5) M) or Krebs-Henseleit solution (control group) and subsequently exposed to cumulative concentrations of U46619 (10(-10) to 10(-6) M). The reversibility of the TXA2-induced vasoconstriction by bupivacaine was also studied. Pretreatment of rings with bupivacaine concentration-dependently diminished TXA2-induced contraction in rat aortic rings. We found no significant differences in relaxing effect of bupivacaine between rings with and without endothelium. Contraction in rings established with U46619 could not be reversed by cumulative concentrations of bupivacaine. Bupivacaine inhibited carbachol-induced vascular relaxation. This study provides experimental evidence that bupivacaine is an endothelium-independent inhibitor of TXA2-induced vasoconstriction of rat thoracic aorta.
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Affiliation(s)
- Klaus Hahnenkamp
- *Department of Anesthesiology and Intensive Care, University Hospital, Mü nster, Germany, the †Department of Anesthesiology, University Hospital, Gent, Belgium, the ‡Institute of Pharmacology and Toxicology, Westfälische-Wilhelms-Universität, Mü nster, Germany, and the §Department of Anesthesiology, Marienhospital, Vechta, Germany
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20
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Ruan KH, Wu J, So SP, Jenkins LA, Ruan CH. NMR structure of the thromboxane A2 receptor ligand recognition pocket. ACTA ACUST UNITED AC 2004; 271:3006-16. [PMID: 15233797 DOI: 10.1111/j.1432-1033.2004.04232.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To overcome the difficulty of characterizing the structures of the extracellular loops (eLPs) of G protein-coupled receptors (GPCRs) other than rhodopsin, we have explored a strategy to generate a three-dimensional structural model for a GPCR, the thromboxane A(2) receptor. This three-dimensional structure was completed by the assembly of the NMR structures of the computation-guided constrained peptides that mimicked the extracellular loops and connected to the conserved seven transmembrane domains. The NMR structure-based model reveals the structural features of the eLPs, in which the second extracellular loop (eLP(2)) and the disulfide bond between the first extracellular loop (eLP(1)) and eLP(2) play a major role in forming the ligand recognition pocket. The eLP(2) conformation is dynamic and regulated by the oxidation and reduction of the disulfide bond, which affects ligand docking in the initial recognition. The reduced form of the thromboxane A(2) receptor experienced a decrease in ligand binding activity due to the rearrangement of the eLP(2) conformation. The ligand-bound receptor was, however, resistant to the reduction inactivation because the ligand covered the disulfide bond and stabilized the eLP(2) conformation. This molecular mechanism of ligand recognition is the first that may be applied to other prostanoid receptors and other GPCRs.
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MESH Headings
- Amino Acid Sequence
- Animals
- Binding Sites
- Disulfides/chemistry
- Humans
- Ligands
- Models, Molecular
- Molecular Sequence Data
- Nuclear Magnetic Resonance, Biomolecular
- Oxidation-Reduction
- Peptides/chemistry
- Peptides/genetics
- Peptides/metabolism
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Receptors, Thromboxane A2, Prostaglandin H2/chemistry
- Receptors, Thromboxane A2, Prostaglandin H2/genetics
- Receptors, Thromboxane A2, Prostaglandin H2/metabolism
- Sequence Alignment
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Affiliation(s)
- Ke-He Ruan
- Vascular Biology Research Center and Division of Hematology, Department of Internal Medicine, The University of Texas Health Science Center, Houston, TX 77030, USA.
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21
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Myatt L, Lye SJ. Expression, localization and function of prostaglandin receptors in myometrium. Prostaglandins Leukot Essent Fatty Acids 2004; 70:137-48. [PMID: 14683689 DOI: 10.1016/j.plefa.2003.04.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Prostaglandins (PGs) play a role in the initiation and maintenance of labor, acting via specific relaxatory or contractile receptors on myometrium. Myometrial response to addition of PGs may be determined by the type and concentration of receptor expressed. Autoradiographic and ligand binding studies suggest a topographic distribution of receptors between fundus, lower segment, and cervix, and that hormonally regulated changes in expression occur with advancing gestation and labor. These receptors have now been cloned and sequenced allowing molecular studies. Current dogma suggests functional regionalization of the pregnant human uterus occurs with the lower segment displaying a contractile phenotype throughout gestation changing to a relaxatory phenotype at labor to allow passage of the fetal head whereas the upper segment has a relaxatory phenotype throughout most of gestation to accommodate the growing fetus and adopts a contractile phenotype for expulsion at labor. Studies to determine the role of PG receptors in this phenomenon are currently underway.
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Affiliation(s)
- Leslie Myatt
- Deparment of Obstetrics and Gynecology, College of Medicine, University of Cincinnati, PO Box 670526, Cincinnati, OH 45267, USA.
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22
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Taylor DM, Halushka PV, Meier GP. Hydrogen bond interactions of a series of N-substituted TXA2 receptor antagonists. Eur J Med Chem 2003; 38:1015-24. [PMID: 14642334 DOI: 10.1016/j.ejmech.2003.07.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A series of N-substituted sulphonamide based thromboxane A2 (TXA2) receptor antagonists were synthesised with the objective to explore the role of hydrogen bond donation properties in the binding of these ligands to the TXA2 receptor. Pharmacological evaluation of these compounds revealed that the binding affinity decreased significantly with the removal of the hydrogen bond donor. This indicates that a hydrogen bond donor is important for the binding of these antagonists to the TXA2 receptor.
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Affiliation(s)
- Dawne M Taylor
- Department of Pharmaceutical Sciences, Medical University of South Carolina, Charleston, SC 29425, USA
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23
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Saha SL, Roche VF, Pendola K, Kearley M, Lei L, Romstedt KJ, Herdman M, Shams G, Kaisare V, Feller DR. Synthesis and in vitro platelet aggregation and TP receptor binding studies on bicyclic 5,8-ethanooctahydroisoquinolines and 5,8-ethanotetrahydroisoquinolines. Bioorg Med Chem 2002; 10:2779-93. [PMID: 12057668 DOI: 10.1016/s0968-0896(02)00101-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Eighteen novel bicyclic 1-substituted benzyl octahydro- and tetrahydroisoquinolines were synthesized and evaluated for human thromboxane A(2)/prostaglandin H(2) (TP) receptor affinity and antagonism of TP receptor-mediated platelet aggregation. In both cases, potency depended more on the presence of methoxy groups on the 1-benzyl moiety than on nitrogen substitution or extent of oxidation of the isoquinoline ring system. The most potent of the bicyclic compounds retained the 5,8-ethanooctahydroisoquinoline ring structure of the parent molecule (1) and required the 3,4,5-trimethoxybenzyl substitution pattern found in the well-characterized tetrahydroisoquinoline antiplatelet agent trimetoquinol. Differences in nitrogen substituent SAR were noted between the mono-methoxylated compounds and the 3,4,5-trimethoxybenzyl derivatives.
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Affiliation(s)
- Shankar L Saha
- School of Pharmacy & Allied Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68005, USA
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Hahnenkamp K, Theilmeier G, Van Aken HK, Hoenemann CW. The effects of local anesthetics on perioperative coagulation, inflammation, and microcirculation. Anesth Analg 2002; 94:1441-7. [PMID: 12032003 DOI: 10.1097/00000539-200206000-00011] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Klaus Hahnenkamp
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Muenster, Albert-Schweitzer-Strasse 33, 48129 Muenster, Germany
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25
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Hahnenkamp K, Theilmeier G, Van Aken HK, Hoenemann CW. The Effects of Local Anesthetics on Perioperative Coagulation, Inflammation, and Microcirculation. Anesth Analg 2002. [DOI: 10.1213/00000539-200206000-00011] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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26
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Turek JW, Halmos T, Sullivan NL, Antonakis K, Le Breton GC. Mapping of a ligand-binding site for the human thromboxane A2 receptor protein. J Biol Chem 2002; 277:16791-7. [PMID: 11877412 DOI: 10.1074/jbc.m105872200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human thromboxane A(2) (TP) receptor, a member of the G protein-coupled receptor superfamily, consists of seven transmembrane segments. Attempts to elucidate the specific segment(s) that define the receptor ligand-binding pocket have produced less than definitive and sometimes conflicting results. On this basis, the present work identified an amino acid sequence of the TP receptor that is directly involved in ligand binding. Mapping of this domain was confirmed by two separate approaches: photoaffinity labeling and site-specific antibodies. The newly synthesized, biotinylated photoaffinity probe, SQBAzide, was first shown to specifically label TP receptor protein. Sequential digestion of this protein with CNBr/trypsin revealed photolabeling of a 2.9-kDa peptide. Using anti-peptide antibodies directed against different regions of the receptor protein, it was established that this peptide represents the predicted cleavage product for CNBr/trypsin and corresponds to amino acids Arg(174)-Met(202) of the receptor protein. Furthermore, antibody screening revealed that inhibition of the amino acid region Cys(183)-Asp(193) was critical for radioligand binding and platelet aggregation, whereas inhibition of Gly(172)-Cys(183) was not. Collectively these findings provide evidence that ligands interact with amino acids contained within the C-terminal portion of the third extracellular domain (ED3) of the receptor protein. This information should be of significant value in the study of TP receptor structure and signaling.
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Affiliation(s)
- Joseph W Turek
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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27
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Rolin S, Dogné JM, Michaux C, Delarge J, Masereel B. Activity of a novel dual thromboxane A(2)receptor antagonist and thromboxane synthase inhibitor (BM-573) on platelet function and isolated smooth muscles. Prostaglandins Leukot Essent Fatty Acids 2001; 65:67-72. [PMID: 11545621 DOI: 10.1054/plef.2001.0290] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The pharmacomodulation of sulfonylureas structurally related to torasemide and characterized by a TXA(2)antagonism led to the synthesis of BM-573. This original molecule showed a high affinity (IC(50)1.3 nM) for the TXA(2)receptor of human platelets in comparison with both reference compounds, SQ-29548 (IC(50)21 nM) and sulotroban (IC(50)930 nM). Moreover, this torasemide derivative was found to be a potent inhibitor of human platelet aggregation induced by arachidonic acid (ED(100)=0.13 microM) or by U-46619 (ED(50)=0.24 microM), a TXA(2)agonist. BM-573 relaxed the isolated rat thoracic aorta (ED(50)=28.4 nM) and guinea-pig trachea (ED(50)=17.7 nM) contracted by U-46619. BM-573 (1 microM) completely reduced the platelet production of TXB(2)induced by arachidonic acid. Finally, BM-573 (30 mg/kg, per os) lost the diuretic properties of torasemide in rats.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Animals
- Antihypertensive Agents/pharmacology
- Aorta/drug effects
- Aorta/enzymology
- Aorta/metabolism
- Arachidonic Acid/antagonists & inhibitors
- Blood Platelets/drug effects
- Blood Platelets/enzymology
- Blood Platelets/metabolism
- Bridged Bicyclo Compounds, Heterocyclic
- Dose-Response Relationship, Drug
- Fatty Acids, Unsaturated
- Guinea Pigs
- Humans
- Hydrazines/pharmacology
- Inhibitory Concentration 50
- Models, Chemical
- Muscle, Smooth/drug effects
- Muscle, Smooth/enzymology
- Muscle, Smooth/metabolism
- Platelet Aggregation/drug effects
- Platelet Aggregation Inhibitors/pharmacology
- Rats
- Rats, Wistar
- Receptors, Thromboxane/antagonists & inhibitors
- Sulfonamides/pharmacology
- Thromboxane-A Synthase/antagonists & inhibitors
- Torsemide
- Trachea/drug effects
- Trachea/enzymology
- Trachea/metabolism
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- S Rolin
- Department of Pharmacy, University of Namur, FUNDP, 61 rue de Bruxelles, B-5000 Namur, Belgium
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28
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Ungrin MD, Carrière MC, Denis D, Lamontagne S, Sawyer N, Stocco R, Tremblay N, Metters KM, Abramovitz M. Key Structural Features of Prostaglandin E2 and Prostanoid Analogs Involved in Binding and Activation of the Human EP1 Prostanoid Receptor. Mol Pharmacol 2001; 59:1446-56. [PMID: 11353805 DOI: 10.1124/mol.59.6.1446] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The structure-activity relationship (SAR) of prostaglandin (PG) E(2) at the human EP(1) prostanoid receptor (designated hEP(1)) was examined via the binding and activation of this receptor by a series of 55 prostanoids and analogs. Using clonal human embryonic kidney 293 cell lines expressing recombinant hEP(1), affinity (K(i)), potency (EC(50)), and efficacy data were obtained using a radioligand competitive binding assay and an aequorin-based calcium functional assay. All compounds behaved as full agonists (90-100% of the response elicited by PGE(2)) in this assay, and the correlation between the K(i) and EC(50) values was highly significant (R(2) = 0.86). The results from the SAR analysis can be summarized as follows: 1) the existence and configuration of hydroxyl groups at the 11 and 15 positions of PGE(2) and prostanoid analog structures play a critical role in agonist activity; 2) the carboxyl group is also important for activity and modification of the carboxylic acid to various esters results in greatly reduced affinity and potency; 3) the activity of structures with moderate or weak potency can be enhanced by modification of the omega-tail; and 4) modifications to the ketone at the 9-position are better tolerated, with 9-deoxy-9-methylene-PGE(2) being the most potent agonist tested in the functional assay. The impact of other modifications on agonist potency is also discussed. The results from this study have identified, for the first time, the key structural features of PGE(2) and related prostanoids and prostanoid analogs necessary for activation of hEP(1).
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Affiliation(s)
- M D Ungrin
- Department of Biochemistry and Molecular Biology, Merck Frosst Center for Therapeutic Research, Pointe Claire-Dorval, Quebec, H9R 4P8 Canada
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29
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Anderson LE, Wu YL, Tsai SJ, Wiltbank MC. Prostaglandin F(2alpha) receptor in the corpus luteum: recent information on the gene, messenger ribonucleic acid, and protein. Biol Reprod 2001; 64:1041-7. [PMID: 11259248 DOI: 10.1095/biolreprod64.4.1041] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The prostaglandin (PG) F(2alpha) receptor (FPr) in the corpus luteum is essential for maintaining normal reproductive cyclicity in many species. Activation of this seven-transmembrane spanning receptor at the end of the cycle leads to a decrease in progesterone and the demise of the corpus luteum (luteolysis). Recently, the gene structure of the FPr in three mammalian species has been elucidated; however, promoter regulation of the gene is still poorly understood. The FPr mRNA is extremely low in steroidogenic follicular cells (theca or granulosa) but is expressed at high levels in the corpus luteum, particularly in the large luteal cells. Treatment with PGF(2alpha) decreased FPr mRNA expression in luteal cells in most species that have been studied. Key amino acids have been suggested to be critical for binding of FPr to PGF(2alpha) based on three-dimensional modeling and comparisons with other G-protein-coupled receptors. Moieties of the PGF(2alpha) molecule that are essential for binding or specificity of binding to the FPr have been identified by radioreceptor binding studies. In this article, recent information is reviewed on the structure of the FPr gene, regulation of luteal FPr mRNA, and receptor/ligand interaction requirements for the FPr protein.
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Affiliation(s)
- L E Anderson
- Endocrinology-Reproductive Physiology Program and Department of Dairy Science, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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30
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Modelling G-protein coupled receptors. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1380-7323(01)80010-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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31
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Abstract
A model of the endothelin G-protein-coupled receptor (ET(A)) has been constructed using a segmented approach. The model was produced using a bovine rhodopsin model as a template for the seven transmembrane alpha-helices. The three cytoplasmic loop regions and the C-terminal region were modeled on NMR structures of corresponding segments from bovine rhodopsin. The three extracellular loops were modeled on homologous loop regions in other proteins of known structure. The N-terminal region was modeled as a three-helix domain based on its homology with a hydrolase protein. To test the model, the FTDOCK algorithm was used to predict the ligand-binding site for the crystal structure of human endothelin. The site of docking is consistent with mutational and biochemical data. The principal sites of interaction in the endothelin ligand all lie on one face of a helix that has been implicated by structure-activity relationship studies as being essential for binding. As further support for the model, attempts to dock bigET, an inactive precursor to endothelin that does not bind to the receptor, found no sites for tight binding. The model of the receptor-ligand complex produced forms a basis for rational drug design of agonists and antagonists for this G-protein-coupled receptor.
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Affiliation(s)
- A J Orry
- Department of Crystallography, Birkbeck College, University of London, London WC1E 7HX, United Kingdom
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32
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Schuster VL, Itoh S, Andrews SW, Burk RM, Chen J, Kedzie KM, Gil DW, Woodward DF. Synthetic modification of prostaglandin f(2alpha) indicates different structural determinants for binding to the prostaglandin F receptor versus the prostaglandin transporter. Mol Pharmacol 2000; 58:1511-6. [PMID: 11093791 DOI: 10.1124/mol.58.6.1511] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Several principles governing the binding of E series prostaglandins to EP receptors have emerged in recent years. The C-1 carboxyl group binds electrostatically to a conserved arginine residue in the seventh transmembrane segment of the receptor. Prostaglandin E analogs involving bioisosteric replacements of the carboxyl group, such as acylsulfonamide, are also active. In addition, structurally similar esters may also exhibit similar affinity, presumably by virtue of hydrogen bonding. Other regions of the substrate molecule appear to bind to other domains of EP receptors, either via hydrophobic interactions or by hydrogen bonding. Less information is available about the structural requirements for substrate binding to FP receptors. Prostanoids also bind to the prostaglandin transporter PGT. In this case, a conserved C-1 carboxyl group is critically important, since C-1 esters exhibit little affinity. Here we examined the binding of chemically diverse PGF(2alpha) structural analogs to the FP receptor and compared these with binding by the PG transporter. PGT recognized a wide range of anionic substituents. In contrast, the carboxylic acid group was essential for optimal binding to the FP receptor, since replacement by larger moieties with a similar pK(a), such as acylsulfonamide and tetrazole, substantially decreased binding affinity. Interestingly, insertion of cyclic substituents in the omega chain increased binding to the FP receptor but reduced affinity for PGT, and substitution for the 15-hydroxyl group produced only a modest reduction in FP receptor binding, but eliminated binding by PGT. Because extracellular PGF(2alpha) may compete for binding between FP receptors and PGT, these findings have implications for designing PGF(2alpha) analogs for treating disease states.
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Affiliation(s)
- V L Schuster
- Department of Medicine, Physiology, and Biophysics, Albert Einstein College of Medicine, Bronx, New York, USA.
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Abstract
Thromboxane A2 is a biologically potent arachidonate metabolite through the cyclooxygenase pathway. It induces platelet aggregation and smooth muscle contraction and may promote mitogenesis and apoptosis of other cells. Its roles in physiological and pathological conditions have been widely documented. The enzyme that catalyzes its synthesis, thromboxane A2 synthase, and the receptors that mediate its actions, thromboxane A2 receptors, are the two key components critical for the functioning of this potent autacoid. Recent molecular biological studies have revealed the structure-function relationship and gene organizations of these proteins as well as genetic and epigenetic factors modulating their gene expression. Future investigation should shed light on detailed molecular signaling events specifying thromboxane A2 actions, and the genetic underpinning of the enzyme and the receptors in health and disease.
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Affiliation(s)
- R F Shen
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for the Genetics of Asthma and Other Complex Diseases, University of Maryland School of Medicine, Baltimore 21201, USA.
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34
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Dogné JM, de Leval X, Neven P, Rolin S, Wauters J, David JL, Delarge J, Massereel B. Effects of a novel non-carboxylic thromboxane A2 receptor antagonist (BM-531) derived from torasemide on platelet function. Prostaglandins Leukot Essent Fatty Acids 2000; 62:311-7. [PMID: 10883063 DOI: 10.1054/plef.2000.0160] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this study we examined the thromboxane A(2)(TXA(2)) receptor antagonist property of BM-531 (N-tert -butyl- N'-[(2-cyclohexylamino-5-nitrobenzene)sulfonyl]urea), a torasemide derivative, on platelet function. The drug affinity for human washed platelet TXA(2)receptors labelled with [(3)H]SQ-29,548 has been determined (IC50: 0.0078 microM) and demonstrated to be higher than sulotroban (IC50: 0.93 microM) and SQ-29,548 (IC50: 0.021 microM). The antiaggregatory potency has been confirmed since we demonstrated that BM-531 prevented platelet aggregation in human citrated platelet-rich plasma induced by arachidonic acid (600 microM) (ED100: 0.125 microM), U-46619, a stable TXA(2)agonist (1 microM) (ED50: 0.482 microM) and collagen (1 microg mL(-1)) (% of inhibition: 42.9% at 10 microM) and inhibited the second wave of ADP (2 microM). Moreover, when BM-531 was incubated in whole blood from healthy donors, the closure time measured by the recently developed platelet function analyser (PFA-100(trade mark)) was significantly prolonged. These results suggest that BM-531 can be regarded as a novel non-carboxylic TXA(2)antagonist with a powerful antiplatelet potency.
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Affiliation(s)
- J M Dogné
- Department of Medicinal Chemistry, University of Liège, Belgium.
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35
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Honemann CW, Lo B, Erera JS, Polanowska-Grabowska R, Gear AR, Durieux M. Local anesthetic effects on TXA2 receptor mediated platelet aggregation using quenched flow aggregometry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 469:269-76. [PMID: 10667341 DOI: 10.1007/978-1-4615-4793-8_40] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- C W Honemann
- Klinik and Poliklinik fur Anasthesiologie and Operative Intensivmedizin, Westfalische Wilhelms Universitat Munster, Germany
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36
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Affiliation(s)
- P V Halushka
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Department of Medicine, Division of Clinical Pharmacology, Medical University of South Carolina, 171 Ashley Ave., Charleston, SC 29425, USA.
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Marusawa H, Setoi H, Kuroda A, Sawada A, Seki J, Motoyama Y, Tanaka H. Synthesis and biological activity of 4-methyl-3,5-dioxane derivatives as thromboxane A2 receptor antagonists. Bioorg Med Chem 1999; 7:2635-45. [PMID: 10632075 DOI: 10.1016/s0968-0896(99)00204-7] [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: 11/26/2022]
Abstract
The synthesis and biological activity of novel 4-methyl-3,5-dioxane analogues are described. All compounds were produced through modification of the substituent formally corresponding to the omega-octenol side chain of thromboxane A2 (TXA2), in reference to the structure of SQ29548. Several compounds were found to be potent TXA2 receptor antagonists. Compound 8b was the most effective inhibitor of 9,11-epoxymethano PGH2 (U-46619)-induced human platelet aggregation (IC50 = 7.4 nM).
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Affiliation(s)
- H Marusawa
- Exploratory Research Laboratories, Fujisawa Pharmaceutical Co., Ltd., Ibaraki, Japan
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38
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Itoh K, Kanzaki K, Ikebe T, Kuroita T, Tomozane H, Sonda S, Sato N, Haga K, Kawakita T. Synthesis and pharmacological evaluation of carboxamide derivatives as selective serotoninergic 5-HT(4) receptor agonists. Eur J Med Chem 1999; 34:977-989. [PMID: 10889321 DOI: 10.1016/s0223-5234(99)00158-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A number of new carboxamide derivatives were synthesized. The affinity of these compounds for the serotoninergic 5-HT(4) receptor was evaluated by use of radioligand-binding techniques. The agonistic activity was evaluated as the contractile effect of the ascending colon isolated from guinea-pigs. Among these compounds, 4-amino-5-chloro-2-methoxy-N-[1-[2-[(methylsulfonyl)amino]ethly]-4-piperidinylmethyl]benzamide (24) showed a high affinity for the 5-HT(4) receptor (Ki = 9.6 nM). Compound 24 displayed a higher affinity for 5-HT(4) receptors than the other receptors, including, 5-HT(3) and dopamine D(2) receptors. In addition, compound 24 was confirmed to be a potent 5-HT(4) receptor agonist (ED(50) = 7.0 nM). An interaction model between compound 24 and 5-HT(4) receptor was proposed.
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Affiliation(s)
- K Itoh
- Research Laboratories, Yoshitomi Pharmaceutical Industries Ltd., 955 Koiwai, Yoshitomi-cho, Chikujo-gun, 871-8550, Fukuoka, Japan
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39
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Wouters J, Durant F, Masereel B. Antagonism of the TXA2 receptor by seratrodast: a structural approach. Bioorg Med Chem Lett 1999; 9:2867-70. [PMID: 10522708 DOI: 10.1016/s0960-894x(99)00490-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The crystal structure of seratrodast (AA-2414), a potent thromboxane A2 (TXA2) receptor antagonist, served as starting point to docking studies with the modeled human TXA2 receptor. This structural approach provides rational basis for the design of new antagonists within the aryl sulfonamide family.
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Affiliation(s)
- J Wouters
- Dept. of Chemistry, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium.
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40
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Masereel B, Damas J, Fontaine J, Lembege M, Lacan F, Nuhrich A, Delarge J, Pochet L, Dogne JM. Thromboxane A2 receptor antagonism in man and rat by a sulphonylcyanoguanidine (BM-144) and a sulphonylurea (BM-500). J Pharm Pharmacol 1999; 51:695-701. [PMID: 10454046 DOI: 10.1211/0022357991772998] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Torasemide, a loop diuretic, has been reported to relax dog coronary artery precontracted by thromboxane A2 (TXA2), an endogenous prostanoid involved in cardiovascular and pulmonary diseases. N-cyano-N'-[[4-(3'-methylphenylamino)pyrid-3-yl]sulphonyl] homopiperidinoamidine (BM-144) and N-isopropyl-N'-[5-nitro-2-(3'-methylphenylamino)-benzenesulphon yl]urea (BM-500), chemically related to torasemide, have been examined for their TXA2 antagonism. The affinity (IC50, the concentration resulting in 50% inhibition) of BM-144 and BM-500 for the TXA2 receptor of washed platelets from man was 0.28 and 0.079 microM, respectively. This is better than for sulotroban (IC50 = 0.93 microM) but less than for SQ-29548 (IC50 = 0.021 microM), two TXA2 antagonists used as reference. The aggregation of platelets from man induced by arachidonic acid was prevented by BM-144 (IC50 = 9.0 microM) and by BM-500 (IC50 = 14.2 microM). Similar results were obtained by use of U-46619, a TXA agonist, as aggregating agent (BM-144, IC50 = 12.9 microM and BM-500, IC50 = 9.9 microM). The contracting effect of U-46619 on rat stomach strip was abolished by BM-144 (IC50 = 1.01 microM) and BM-500 (IC50 = 2.54 microM). Both drugs (BM-144: IC50 = 0.12 microM and BM-500: IC50 = 0.19 microM) also relaxed rat aorta precontracted by U-46619; both were more potent than sulotroban (IC50 = 1.62 microM). The two torasemide derivatives (100 microM) did not significantly affect the myo-stimulating effect of some prostaglandins (PGE2, PGI2, PGF2alpha) or aorta contraction elicited by KCl (30 mM). They did not modify rat diuresis after administration of a 30-mg kg(-1) dose. In conclusion, BM-144 and BM-500 can be regarded as novel non-carboxylic TXA2 receptor antagonists and offer a novel template for the design of more potent molecules.
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Affiliation(s)
- B Masereel
- Department of Pharmacy, University of Namur, FUNDP, Belgium
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41
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Itoh K, Kanzaki K, Ikebe T, Kuroita T, Tomozane H, Sonda S, Sato N, Haga K, Kawakita T. Synthesis and pharmacological evaluation of carboxamide derivatives as selective serotoninergic 5-HT4 receptor agonists. Eur J Med Chem 1999. [DOI: 10.1016/s0223-5234(99)80083-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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42
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Stillman BA, Audoly L, Breyer RM. A conserved threonine in the second extracellular loop of the human EP2 and EP4 receptors is required for ligand binding. Eur J Pharmacol 1998; 357:73-82. [PMID: 9788776 DOI: 10.1016/s0014-2999(98)00522-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
G protein coupled receptors for prostaglandins are activated when agonists are bound to a binding pocket formed in part by the seven transmembrane domains. Recent studies have determined that substitution of a conserved threonine in the second extracellular loop of the prostaglandin EP3 receptor resulted in increased affinity for ligands with a C1 methyl ester moiety. The homologous threonine in the second extracellular loop of the human prostaglandin EP2 and EP4 receptors was mutated to alanine. When expressed in COS1 cells, detectable radioligand binding at both of these receptors bearing the threonine to alanine substitution (EP2T185A; EP4T168A) was abolished, as well as the receptors' ability to stimulate intracellular [cAMP]. In contrast, EP2 and EP4 receptors bearing conservative threonine to serine mutations (EP2T185S; EP4T168S) displayed Kd values for [3H]prostaglandin E2 similar to wild type receptors: 8.8 +/- 0.7 nM for EP2T185S compared to 12.9 +/- 1.2 nM for EP2 wild type; 2.0 +/- 0.8 nM for EP4T168S compared to 0.9 +/- 0.3 nM for the EP4 wild type receptor. The EC50 values for cAMP stimulation were 1.3 +/- 0.6 nM for EP2 wild type; 2.7 +/- 1.3 nM for EP2T185S; 1.1 +/- 0.3 nM for EP4 wild type; and 1.4 +/- 0.33 nM for EP4T168S. These studies suggest a critical role for the hydroxyl moiety on these conserved threonine residues at position 168/185 of the second extracellular loop in prostaglandin receptor-ligand interactions.
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Affiliation(s)
- B A Stillman
- Department of Pharmacology and Vanderbilt Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232-2372, USA
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43
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Albuquerque MG, Hopfinger AJ, Barreiro EJ, de Alencastro RB. Four-dimensional quantitative structure-activity relationship analysis of a series of interphenylene 7-oxabicycloheptane oxazole thromboxane A2 receptor antagonists. JOURNAL OF CHEMICAL INFORMATION AND COMPUTER SCIENCES 1998; 38:925-38. [PMID: 9770304 DOI: 10.1021/ci980093s] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of 39 (a training set of 29 and a test set of 10) interphenylene 7-oxabicyclo [2.2.1]heptane oxazole thromboxane A2 (TXA2) receptor antagonists were studied using four-dimensional quantitative structure-activity relationship (4D-QSAR) analysis. Two thousand conformations of each analogue were sampled to generate a conformational energy profile (CEP) from a molecular dynamic simulation (MDS) of 100,000 trajectory states. Each conformation was placed in a grid cell lattice for each of six trial alignments. Cubic grid cell sizes of 1 and 2 A were considered. The frequency of occupation of each grid cell was computed for each of seven types of pharmacophoric group classes of atoms of each compound. These grid cell occupancy descriptors (GCODs) were then used as independent variables in constructing three-dimensional (3D)-QSAR models after data reduction. The types of data reduction included doing no reducing, reduction based on individual GCOD correlation with activity, and reduction from minimum variance constraints over the GCOD population. The 3D-QSAR models were generated and evaluated by a scheme that combines a genetic algorithm (GA) optimization with partial least squares (PLS) regression. The 3D-QSAR models were evaluated by cross-validation using the leave-one-out technique. The cross-validated correlation coefficient, Q2, ranged from 0.27 to 0.86. The models are not from chance correlation because a scrambled data set was generated and evaluated (Q2 = 0.25-0.37). A composite 3D-QSAR model was constructed using the best models derived from GCODs of both 1 and 2 A grid cell size lattices. The 3D-QSAR models provide detailed 3D pharmacophore requirements in terms of atom types and corresponding locations needed for high TXA2 inhibition activity. Specific sites in space that should not be occupied by an active inhibitor are also specified. The GCOD measures for the compounds in the training set permit reference points regarding which pharmacophore sites can provide the largest boosts in inhibition activity relative to the existing analogues.
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Affiliation(s)
- M G Albuquerque
- Laboratory of Molecular Modeling and Design, College of Pharmacy, University of Illinois at Chicago 60612-7231, USA
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Vilven JC, Domalewski M, Prossnitz ER, Ye RD, Muthukumaraswamy N, Harris RB, Freer RJ, Sklar LA. Strategies for positioning fluorescent probes and crosslinkers on formyl peptide ligands. J Recept Signal Transduct Res 1998; 18:187-221. [PMID: 9651885 DOI: 10.3109/10799899809047744] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Chemoattractant receptors represent a major subset of the G-protein coupled receptor (GPCR) family. One of the best characterized, the N-formyl peptide receptor (FPR), participates in host defense responses of neutrophils. The features of the ligand which regulate its interaction with the FPR are well-known. By manipulating these features we have developed new ligands to probe structural and mechanistic aspects of the peptide-receptor interaction. Three ligand groups have been developed: 1) ligands containing a Lys residue located in positions 2 through 7 that can be conjugated to FITC (N-formyl-Met1-Lys2-Phe3-Phe4, N-formyl-Met1-Leu2-Lys3-Phe4, N-formyl-Met1-Leu2-Phe3-Lys4, N-formyl-Met1-Leu2-Phe3-Phe4-Lys5, N-formyl-nLeu1-Leu2-Phe3-nLeu4-Tyr5-Lys6 and N-formyl-Met1-Leu2-Phe3-Phe4-Gly5-Gly6-Lys7; 2) fluorescent pentapeptide ligands (N-formyl-Met-X-Phe-Phe-Lys(FITC) where X = Leu, Ala, Val or Gly); and 3) small crosslinking ligands where the photoaffinity crosslinker 4-azidosalicylic acid (ASA) was conjugated to Lys in positions 3 and 4 and p-benzoyl-phenylalanine (Bpa) was located in position 2 in N-formyl-Met1-Bpa2-Phe3-Tyr4. The peptides were characterized according to activity and affinity in human neutrophils and cell lines transfected with FPR. All of the peptides were agonists, with parallel affinity and activity. In the first group, the peptide activity decreases as Lys is placed closer to the N-formyl group and the activity is improved by 1-3 orders of magnitude by conjugation with FITC. In the second group, the dissociation rate of the peptide from the receptor increases as position 2 is replaced by aliphatic amino acids with smaller alkyl groups. In the third group, crosslinking ligands remain biologically active, display nM affinity and covalently label the FPR.
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Affiliation(s)
- J C Vilven
- Cancer Center and Pathology, University of New Mexico Health Sciences Center, Albuquerque, USA
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Filizola M, Perez JJ, Cartenì-Farina M. BUNDLE: a program for building the transmembrane domains of G-protein-coupled receptors. J Comput Aided Mol Des 1998; 12:111-8. [PMID: 9690171 DOI: 10.1023/a:1007969112988] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The only information available at present about the structural features of G-protein-coupled receptors (GPCRs) comes from low resolution electron density maps of rhodopsin obtained from electron microscopy studies on 2D crystals. Despite their low resolution, maps can be used to extract information about transmembrane helix relative positions and their tilt. This information, together with a reliable algorithm to assess the residues involved in each of the membrane spanning regions, can be used to construct a 3D model of the transmembrane domains of rhodopsin at atomic resolution. In the present work, we describe an automated procedure applicable to generate such a model and, in general, to construct a 3D model of any given GPCR with the only assumption that it adopts the same helix arrangement as in rhodopsin. The present approach avoids uncertainties associated with other procedures available for constructing models of GPCRs based on a template, since sequence identity among GPCRs of different families in most of the cases is not significant. The steps involved in the construction of the model are: (i) locate the centers of the helices according to the low-resolution electron density map; (ii) compute the tilt of each helix based on the elliptical shape observed by each helix in the map; (iii) define a local coordinate system for each of the helices; (iv) bring them together in an antiparallel orientation; (v) rotate each helix through the helical axis in such a way that its hydrophobic moment points in the same direction of the bisector formed between three consecutive helices in the bundle; (vi) rotate each helix through an axis perpendicular to the helical one to assign a proper tilt; and (vii) translate each helix to its center deduced from the projection map.
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Affiliation(s)
- M Filizola
- Departament d'Enginyeria Química, UPC, ETS d'Enginyers Industrials, Barcelona, Spain
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Tai HH, Huang C, Chiang N. Structure and function of prostanoid receptors as revealed by site-directed mutagenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 407:205-9. [PMID: 9321954 DOI: 10.1007/978-1-4899-1813-0_31] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- H H Tai
- Division of Medicinal Chemistry and Pharmaceutics, College of Pharmacy, University of Kentucky, Lexington 40536-0082, USA
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Chang CS, Negishi M, Nishigaki N, Ichikawa A. Characterization of functional interaction of carboxylic acid group of agonists and arginine of the seventh transmembrane domains of four prostaglandin E receptor subtypes. PROSTAGLANDINS 1997; 54:437-46. [PMID: 9271782 DOI: 10.1016/s0090-6980(97)00064-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Prostaglandin (PG) E2 binds to four PGE receptor subtypes, EP1, EP2, EP3 and EP4, and induces a variety of functions through the interaction of carboxylic acid of PGE2 and Arg residue in the seventh transmembrane domain of the receptor. To assess the role of the interaction of the carboxylic acid group of agonists and the Arg residue, which can form both ionic bonding and hydrogen bonding as a hydrogen donor, we examined the agonist activities of three types of agonist, PGE2 with a negatively charged carboxylic acid, PGE2 methylester, which is a hydrogen acceptor, and 1-OH PGE2, which can accept as well as donate hydrogen but prefers to donate hydrogen rather than accept it, for four PGE receptor subtypes. Although PGE2 methylester had slightly lower agonist activities than PGE2 for EP1 and EP4 receptors, PGE2 and its methylester showed the same agonist activities for EP2 and EP3 receptors, indicating that PGE2 methylester is a potent agonist for all of the four subtypes. In contrast, 1-OH PGE2 was a very weak agonist for all receptors. These findings demonstrate that the hydrogen bonding interaction of agonists and the Arg residue is generally sufficient for the functional activation of all of the PGE receptor subtypes.
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Affiliation(s)
- C S Chang
- Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Japan
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Audoly L, Breyer RM. The second extracellular loop of the prostaglandin EP3 receptor is an essential determinant of ligand selectivity. J Biol Chem 1997; 272:13475-8. [PMID: 9153190 DOI: 10.1074/jbc.272.21.13475] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The prostaglandin EP3 receptor binds Prostaglandin E2 in a ligand binding pocket formed in part by seven transmembrane alpha-helices. The present studies demonstrate that the second extracellular loop of the receptor is involved in prostanoid ligand recognition as well. Site-directed mutagenesis of seven conserved residues clustered in the amino portion of the second extracellular loop was performed. Receptors with single amino acid substitutions at each of these positions were transiently transfected into HEK293tsA201 cells, their ligand binding profiles assessed, and each receptor was tested for its ability to decrease intracellular cAMP levels. Substitution of Trp199 or Thr202 with alanine resulted in receptors with increases in affinity up to 128-fold for prostanoid compounds with a C1 methyl ester but wild type affinities for natural prostanoid ligands that have a carboxylate moiety at the C1 position. In contrast, substitution of Pro200 with serine caused a loss of selectivity up to 20-fold for naturally occurring prostanoid agonists as compared with the wild type EP3 receptor: the PS200 receptor displayed a decrease in affinity for E-ring compounds and an increase in affinity for F- and D-ring compounds. The EC50 for inhibition of cAMP remained unchanged for each receptor tested.
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Affiliation(s)
- L Audoly
- Division of Nephrology and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2372, USA
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Chang C, Negishi M, Nishigaki N, Ichikawa A. Functional interaction of the carboxylic acid group of agonists and the arginine residue of the seventh transmembrane domain of prostaglandin E receptor EP3 subtype. Biochem J 1997; 322 ( Pt 2):597-601. [PMID: 9065782 PMCID: PMC1218231 DOI: 10.1042/bj3220597] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Prostaglandin (PG) E2 binds to PGE receptor EP3 subtype and induces Gi activity. To assess the role of the interaction of the carboxylic acid group of agonists and its putative binding site, Arg-309 in the seventh transmembrane domain of EP3alpha receptor, in receptor activation, we have mutated the positively charged Arg-309 to the polar but uncharged Gln (EP3alpha-R309Q) and Asn (EP3alpha-R309N), and to the non-polar Leu (EP3alpha-R309L). Wild-type, EP3alpha-R309Q and EP3alpha-R309N receptors showed high-affinity binding for PGE2, but the EP3alpha-R309L receptor showed very-low-affinity binding. Guanosine 5'-[gamma-thio]triphosphate increased the PGE2 binding to the wild-type receptor, decreased the binding to EP3alpha-R309Q and EP3alpha-R309N receptors, but did not affect that to the EP3alpha-R309L receptor. Furthermore we examined the Gi activities of two types of EP3 agonist, TEI-3356 with a negatively charged carboxylic acid, and TEI-4343, a methyl ester of TEI-3356 with an uncharged but polar group, towards those receptors. Both agonists inhibited the forskolin-stimulated cAMP formation in wild-type, EP3alpha-R309Q and EP3alpha-R309N receptors in the same concentration-dependent manner, but the agonists showed a very low inhibition of EP3alpha-R309L receptor. These findings demonstrate that the hydrogen-bonding interaction of EP3 agonists and residue 309 in the seventh transmembrane domain of the EP3alpha receptor is sufficient for the functional activation of the EP3alpha receptor.
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Affiliation(s)
- C Chang
- Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Japan
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Sagara T, Egashira H, Okamura M, Fujii I, Shimohigashi Y, Kanematsu K. Ligand recognition in mu opioid receptor: experimentally based modeling of mu opioid receptor binding sites and their testing by ligand docking. Bioorg Med Chem 1996; 4:2151-66. [PMID: 9022978 DOI: 10.1016/s0968-0896(96)00219-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
For three-dimensional understanding of the mechanisms that control potency and selectivity of the ligand binding at the atomic level, we have analysed opioid receptor-ligand interaction based on the receptor's 3D model. As a first step, we have constructed molecular models for the multiple opioid receptor subtypes using bacteriorhodopsin as a template. The S-activated dihydromorphine derivatives should serve as powerful tools in mapping the three-dimensional structure of the mu opioid receptor, including the nature of the agonist-mediated conformational change that permits G protein-coupling to "second messenger' effector molecules, and in identifying specific ligand-binding contacts with the mu opioid receptor. The analyses of the interactions of some opioid ligands with the predicted ligand binding sites are consistent with the results of the affinity labeling experiments.
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Affiliation(s)
- T Sagara
- Institute of Synthetic Organic Chemistry, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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