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Tscharre M, Michelson AD, Gremmel T. Novel Antiplatelet Agents in Cardiovascular Disease. J Cardiovasc Pharmacol Ther 2020; 25:191-200. [DOI: 10.1177/1074248419899314] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Antiplatelet therapy reduces atherothrombotic risk and has therefore become a cornerstone in the treatment of cardiovascular disease. Aspirin, adenosine diphosphate P2Y12 receptor antagonists, glycoprotein IIb/IIIa inhibitors, and the thrombin receptor blocker vorapaxar are effective antiplatelet agents but significantly increase the risk of bleeding. Moreover, atherothrombotic events still impair the prognosis of many patients with cardiovascular disease despite established antiplatelet therapy. Over the last years, advances in the understanding of thrombus formation and hemostasis led to the discovery of various new receptors and signaling pathways of platelet activation. As a consequence, many new antiplatelet agents with high antithrombotic efficacy and supposedly only moderate effects on regular hemostasis have been developed and yielded promising results in preclinical and early clinical studies. Although their long journey from animal studies to randomized clinical trials and finally administration in daily clinical routine has just begun, some of the new agents may in the future become meaningful additions to the pharmacological armamentarium in cardiovascular disease.
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Affiliation(s)
- Maximilian Tscharre
- Department of Internal Medicine, Cardiology and Nephrology, Landesklinikum Wiener Neustadt, Wiener Neustadt, Austria
- Institute of Vascular Medicine and Cardiac Electrophysiology, Karl Landsteiner Society, St Poelten, Austria
| | - Alan D. Michelson
- Center for Platelet Research Studies, Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA, USA
| | - Thomas Gremmel
- Department of Internal Medicine, Cardiology and Nephrology, Landesklinikum Wiener Neustadt, Wiener Neustadt, Austria
- Institute of Vascular Medicine and Cardiac Electrophysiology, Karl Landsteiner Society, St Poelten, Austria
- Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria
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2
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Romanenko VD. α-Heteroatom-substituted gem-Bisphosphonates: Advances in the Synthesis and Prospects for Biomedical Application. CURR ORG CHEM 2019. [DOI: 10.2174/1385272823666190401141844] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Functionalized gem-bisphosphonic acid derivatives being pyrophosphate isosteres are of great synthetic and biological interest since they are currently the most important class of drugs developed for the treatment of diseases associated with the disorder of calcium metabolism, including osteoporosis, Paget’s disease, and hypercalcemia. In this article, we will try to give an in-depth overview of the methods for obtaining α- heteroatom-substituted methylenebisphosphonates and acquaint the reader with the synthetic strategies that are used to develop biologically important compounds of this type.
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Affiliation(s)
- Vadim D. Romanenko
- V. P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, 1-Murmanska Street, Kyiv-94, 02660, Ukraine
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3
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Gremmel T, Yanachkov IB, Yanachkova MI, Wright GE, Wider J, Undyala VVR, Michelson AD, Frelinger AL, Przyklenk K. Synergistic Inhibition of Both P2Y1 and P2Y12 Adenosine Diphosphate Receptors As Novel Approach to Rapidly Attenuate Platelet-Mediated Thrombosis. Arterioscler Thromb Vasc Biol 2016; 36:501-9. [PMID: 26743169 PMCID: PMC4767596 DOI: 10.1161/atvbaha.115.306885] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 12/22/2015] [Indexed: 12/30/2022]
Abstract
OBJECTIVE Unlike currently approved adenosine diphosphate receptor antagonists, the new diadenosine tetraphosphate derivative GLS-409 targets not only P2Y12 but also the second human platelet adenosine diphosphate receptor P2Y1 and may, therefore, be a promising antiplatelet drug candidate. The current study is the first to investigate the in vivo antithrombotic effects of GLS-409. APPROACH AND RESULTS We studied (1) the in vivo effects of GLS-409 on agonist-stimulated platelet aggregation in anesthetized rats, (2) the antithrombotic activity of GLS-409 and the associated effect on the bleeding time in a canine model of platelet-mediated coronary artery thrombosis, and (3) the inhibition of agonist-stimulated platelet aggregation by GLS-409 versus selective P2Y1 and P2Y12 inhibition in vitro in samples from healthy human subjects before and 2 hours after aspirin intake. In vivo treatment with GLS-409 significantly inhibited adenosine diphosphate- and collagen-stimulated platelet aggregation in rats. Further, GLS-409 attenuated cyclic flow variation, that is, platelet-mediated thrombosis, in vivo in our canine model of unstable angina. The improvement in coronary patency was accompanied by a nonsignificant 30% increase in bleeding time. Of note, GLS-409 exerted its effects without affecting rat and canine hemodynamics. Finally, in vitro treatment with GLS-409 showed effects similar to that of cangrelor and the combination of cangrelor with the selective P2Y1 inhibitor MRS 2179 on agonist-stimulated platelet aggregation in human platelet-rich plasma and whole blood before and 2 hours after aspirin intake. CONCLUSIONS Synergistic inhibition of both P2Y1 and P2Y12 adenosine diphosphate receptors by GLS-409 immediately attenuates platelet-mediated thrombosis and effectively blocks agonist-stimulated platelet aggregation irrespective of concomitant aspirin therapy.
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Affiliation(s)
- Thomas Gremmel
- From the Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (T.G., A.D.M., A.L.F.); Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.G.); GLSynthesis Inc, Worcester, MA (I.B.Y., M.I.Y., G.E.W.); and Cardiovascular Research Institute and Departments of Physiology and Emergency Medicine, Wayne State University School of Medicine, Detroit, MI (J.W., V.V.R.U., K.P.).
| | - Ivan B Yanachkov
- From the Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (T.G., A.D.M., A.L.F.); Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.G.); GLSynthesis Inc, Worcester, MA (I.B.Y., M.I.Y., G.E.W.); and Cardiovascular Research Institute and Departments of Physiology and Emergency Medicine, Wayne State University School of Medicine, Detroit, MI (J.W., V.V.R.U., K.P.)
| | - Milka I Yanachkova
- From the Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (T.G., A.D.M., A.L.F.); Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.G.); GLSynthesis Inc, Worcester, MA (I.B.Y., M.I.Y., G.E.W.); and Cardiovascular Research Institute and Departments of Physiology and Emergency Medicine, Wayne State University School of Medicine, Detroit, MI (J.W., V.V.R.U., K.P.)
| | - George E Wright
- From the Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (T.G., A.D.M., A.L.F.); Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.G.); GLSynthesis Inc, Worcester, MA (I.B.Y., M.I.Y., G.E.W.); and Cardiovascular Research Institute and Departments of Physiology and Emergency Medicine, Wayne State University School of Medicine, Detroit, MI (J.W., V.V.R.U., K.P.)
| | - Joseph Wider
- From the Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (T.G., A.D.M., A.L.F.); Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.G.); GLSynthesis Inc, Worcester, MA (I.B.Y., M.I.Y., G.E.W.); and Cardiovascular Research Institute and Departments of Physiology and Emergency Medicine, Wayne State University School of Medicine, Detroit, MI (J.W., V.V.R.U., K.P.)
| | - Vishnu V R Undyala
- From the Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (T.G., A.D.M., A.L.F.); Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.G.); GLSynthesis Inc, Worcester, MA (I.B.Y., M.I.Y., G.E.W.); and Cardiovascular Research Institute and Departments of Physiology and Emergency Medicine, Wayne State University School of Medicine, Detroit, MI (J.W., V.V.R.U., K.P.)
| | - Alan D Michelson
- From the Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (T.G., A.D.M., A.L.F.); Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.G.); GLSynthesis Inc, Worcester, MA (I.B.Y., M.I.Y., G.E.W.); and Cardiovascular Research Institute and Departments of Physiology and Emergency Medicine, Wayne State University School of Medicine, Detroit, MI (J.W., V.V.R.U., K.P.)
| | - Andrew L Frelinger
- From the Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (T.G., A.D.M., A.L.F.); Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.G.); GLSynthesis Inc, Worcester, MA (I.B.Y., M.I.Y., G.E.W.); and Cardiovascular Research Institute and Departments of Physiology and Emergency Medicine, Wayne State University School of Medicine, Detroit, MI (J.W., V.V.R.U., K.P.)
| | - Karin Przyklenk
- From the Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (T.G., A.D.M., A.L.F.); Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.G.); GLSynthesis Inc, Worcester, MA (I.B.Y., M.I.Y., G.E.W.); and Cardiovascular Research Institute and Departments of Physiology and Emergency Medicine, Wayne State University School of Medicine, Detroit, MI (J.W., V.V.R.U., K.P.)
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Burnstock G. Blood cells: an historical account of the roles of purinergic signalling. Purinergic Signal 2015; 11:411-34. [PMID: 26260710 PMCID: PMC4648797 DOI: 10.1007/s11302-015-9462-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 07/23/2015] [Indexed: 12/17/2022] Open
Abstract
The involvement of purinergic signalling in the physiology of erythrocytes, platelets and leukocytes was recognised early. The release of ATP and the expression of purinoceptors and ectonucleotidases on erythrocytes in health and disease are reviewed. The release of ATP and ADP from platelets and the expression and roles of P1, P2Y(1), P2Y(12) and P2X1 receptors on platelets are described. P2Y(1) and P2X(1) receptors mediate changes in platelet shape, while P2Y(12) receptors mediate platelet aggregation. The changes in the role of purinergic signalling in a variety of disease conditions are considered. The successful use of P2Y(12) receptor antagonists, such as clopidogrel and ticagrelor, for the treatment of thrombosis, myocardial infarction and stroke is discussed.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK.
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Australia.
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Yanachkov IB, Chang H, Yanachkova MI, Dix EJ, Berny-Lang MA, Gremmel T, Michelson AD, Wright GE, Frelinger AL. New highly active antiplatelet agents with dual specificity for platelet P2Y1 and P2Y12 adenosine diphosphate receptors. Eur J Med Chem 2015; 107:204-18. [PMID: 26588064 DOI: 10.1016/j.ejmech.2015.10.055] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 10/27/2015] [Accepted: 10/30/2015] [Indexed: 10/25/2022]
Abstract
Currently approved platelet adenosine diphosphate (ADP) receptor antagonists target only the platelet P2Y12 receptor. Moreover, especially in patients with acute coronary syndromes, there is a strong need for rapidly acting and reversible antiplatelet agents in order to minimize the risk of thrombotic events and bleeding complications. In this study, a series of new P(1),P(4)-di(adenosine-5') tetraphosphate (Ap4A) derivatives with modifications in the base and in the tetraphosphate chain were synthesized and evaluated with respect to their effects on platelet aggregation and function of the platelet P2Y1, P2Y12, and P2X1 receptors. The resulting structure-activity relationships were used to design Ap4A analogs which inhibit human platelet aggregation by simultaneously antagonizing both P2Y1 and P2Y12 platelet receptors. Unlike Ap4A, the analogs do not activate platelet P2X1 receptors. Furthermore, the new compounds exhibit fast onset and offset of action and are significantly more stable than Ap4A to degradation in plasma, thus presenting a new promising class of antiplatelet agents.
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Affiliation(s)
| | - Hung Chang
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA; Hematology Division, Chang Gung Memorial Hospital, Chang Gung University, Taipei, Taiwan
| | | | | | - Michelle A Berny-Lang
- Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Thomas Gremmel
- Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Alan D Michelson
- Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA; Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
| | | | - Andrew L Frelinger
- Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA; Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
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Modeling ligand recognition at the P2Y12 receptor in light of X-ray structural information. J Comput Aided Mol Des 2015. [PMID: 26194851 DOI: 10.1007/s10822-015-9858-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The G protein-coupled P2Y12 receptor (P2Y12R) is an important antithrombotic target and of great interest for pharmaceutical discovery. Its recently solved, highly divergent crystallographic structures in complex either with nucleotides (full or partial agonist) or with a nonnucleotide antagonist raise the question of which structure is more useful to understand ligand recognition. Therefore, we performed extensive molecular modeling studies based on these structures and mutagenesis, to predict the binding modes of major classes of P2Y12R ligands previously reported. Various nucleotide derivatives docked readily to the agonist-bound P2Y12R, but uncharged nucleotide-like antagonist ticagrelor required a hybrid receptor resembling the agonist-bound P2Y12R except for the top portion of TM6. Supervised molecular dynamics (SuMD) of ticagrelor binding indicated interactions with the extracellular regions of P2Y12R, defining possible meta-binding sites. Ureas, sulfonylureas, sulfonamides, anthraquinones and glutamic acid piperazines docked readily to the antagonist-bound P2Y12R. Docking dinucleotides at both agonist- and antagonist-bound structures suggested interactions with two P2Y12R pockets. Thus, our structure-based approach consistently rationalized the main structure-activity relationships within each ligand class, giving useful information for designing improved ligands.
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Modica MV, Lombardo F, Franchini P, Oliverio M. The venomous cocktail of the vampire snail Colubraria reticulata (Mollusca, Gastropoda). BMC Genomics 2015; 16:441. [PMID: 26054852 PMCID: PMC4460706 DOI: 10.1186/s12864-015-1648-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 05/20/2015] [Indexed: 01/13/2023] Open
Abstract
Background Hematophagy arose independently multiple times during metazoan evolution, with several lineages of vampire animals particularly diversified in invertebrates. However, the biochemistry of hematophagy has been studied in a few species of direct medical interest and is still underdeveloped in most invertebrates, as in general is the study of venom toxins. In cone snails, leeches, arthropods and snakes, the strong target specificity of venom toxins uniquely aligns them to industrial and academic pursuits (pharmacological applications, pest control etc.) and provides a biochemical tool for studying biological activities including cell signalling and immunological response. Neogastropod snails (cones, oyster drills etc.) are carnivorous and include active predators, scavengers, grazers on sessile invertebrates and hematophagous parasites; most of them use venoms to efficiently feed. It has been hypothesized that trophic innovations were the main drivers of rapid radiation of Neogastropoda in the late Cretaceous. We present here the first molecular characterization of the alimentary secretion of a non-conoidean neogastropod, Colubraria reticulata. Colubrariids successfully feed on the blood of fishes, throughout the secretion into the host of a complex mixture of anaesthetics and anticoagulants. We used a NGS RNA-Seq approach, integrated with differential expression analyses and custom searches for putative secreted feeding-related proteins, to describe in detail the salivary and mid-oesophageal transcriptomes of this Mediterranean vampire snail, with functional and evolutionary insights on major families of bioactive molecules. Results A remarkably low level of overlap was observed between the gene expression in the two target tissues, which also contained a high percentage of putatively secreted proteins when compared to the whole body. At least 12 families of feeding-related proteins were identified, including: 1) anaesthetics, such as ShK Toxin-containing proteins and turripeptides (ion-channel blockers), Cysteine-rich secretory proteins (CRISPs), Adenosine Deaminase (ADA); 2) inhibitors of primary haemostasis, such as novel vWFA domain-containing proteins, the Ectonucleotide pyrophosphatase/phosphodiesterase family member 5 (ENPP5) and the wasp Antigen-5; 3) anticoagulants, such as TFPI-like multiple Kunitz-type protease inhibitors, Peptidases S1 (PS1), CAP/ShKT domain-containing proteins, Astacin metalloproteases and Astacin/ShKT domain-containing proteins; 4) additional proteins, such the Angiotensin-Converting Enzyme (ACE: vasopressive) and the cytolytic Porins. Conclusions Colubraria feeding physiology seems to involve inhibitors of both primary and secondary haemostasis, anaesthetics, a vasoconstrictive enzyme to reduce feeding time and tissue-degrading proteins such as Porins and Astacins. The complexity of Colubraria venomous cocktail and the divergence from the arsenal of the few neogastropods studied to date (mostly conoideans) suggest that biochemical diversification of neogastropods might be largely underestimated and worth of extensive investigation. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1648-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Maria Vittoria Modica
- Department of Biology and Biotechnologies "C. Darwin", Sapienza University, I-00185, Rome, Italy.
| | - Fabrizio Lombardo
- Department of Public Health and Infectious Diseases, Sapienza University, I-00185, Rome, Italy.
| | - Paolo Franchini
- Department of Biology, University of Konstanz, D-78745, Konstanz, Germany.
| | - Marco Oliverio
- Department of Biology and Biotechnologies "C. Darwin", Sapienza University, I-00185, Rome, Italy.
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Jacobson KA, Paoletta S, Katritch V, Wu B, Gao ZG, Zhao Q, Stevens RC, Kiselev E. Nucleotides Acting at P2Y Receptors: Connecting Structure and Function. Mol Pharmacol 2015; 88:220-30. [PMID: 25837834 DOI: 10.1124/mol.114.095711] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 04/02/2015] [Indexed: 12/23/2022] Open
Abstract
Eight G protein-coupled P2Y receptor (P2YR) subtypes are important physiologic mediators. The human P2YRs are fully activated by ATP (P2Y2 and P2Y11), ADP (P2Y1, P2Y12, and P2Y13), UTP (P2Y2 and P2Y4), UDP (P2Y6 and P2Y14), and UDP glucose (P2Y14). Their structural elucidation is progressing rapidly. The X-ray structures of three ligand complexes of the Gi-coupled P2Y12R and two of the Gq-coupled P2Y1Rs were recently determined and will be especially useful in structure-based ligand design at two P2YR subfamilies. These high-resolution structures, which display unusual binding site features, complement mutagenesis studies for probing ligand recognition and activation. The structural requirements for nucleotide agonist recognition at P2YRs are relatively permissive with respect to the length of the phosphate moiety, but less so with respect to base recognition. Nucleotide-like antagonists and partial agonists are also known for P2Y1, P2Y2, P2Y4, and P2Y12Rs. Each P2YR subtype has the ability to be activated by structurally bifunctional agonists, such as dinucleotides, typically, dinucleoside triphosphates or tetraphosphates, and nucleoside polyphosphate sugars (e.g., UDP glucose) as well as the more conventional mononucleotide agonists. A range of dinucleoside polyphosphates, from triphosphates to higher homologs, occurs naturally. Earlier modeling predictions of the P2YRs were not very accurate, but recent findings have provided much detailed structural insight into this receptor family to aid in the rational design of new drugs.
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Affiliation(s)
- Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (K.A.J., S.P., Z.-G.G., E.K.); The Bridge Institute, Dana and David Dornsife School of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California (V.K., R.C.S.); and Chinese Academy of Sciences Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China (B.W., Q.Z.)
| | - Silvia Paoletta
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (K.A.J., S.P., Z.-G.G., E.K.); The Bridge Institute, Dana and David Dornsife School of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California (V.K., R.C.S.); and Chinese Academy of Sciences Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China (B.W., Q.Z.)
| | - Vsevolod Katritch
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (K.A.J., S.P., Z.-G.G., E.K.); The Bridge Institute, Dana and David Dornsife School of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California (V.K., R.C.S.); and Chinese Academy of Sciences Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China (B.W., Q.Z.)
| | - Beili Wu
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (K.A.J., S.P., Z.-G.G., E.K.); The Bridge Institute, Dana and David Dornsife School of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California (V.K., R.C.S.); and Chinese Academy of Sciences Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China (B.W., Q.Z.)
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (K.A.J., S.P., Z.-G.G., E.K.); The Bridge Institute, Dana and David Dornsife School of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California (V.K., R.C.S.); and Chinese Academy of Sciences Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China (B.W., Q.Z.)
| | - Qiang Zhao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (K.A.J., S.P., Z.-G.G., E.K.); The Bridge Institute, Dana and David Dornsife School of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California (V.K., R.C.S.); and Chinese Academy of Sciences Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China (B.W., Q.Z.)
| | - Raymond C Stevens
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (K.A.J., S.P., Z.-G.G., E.K.); The Bridge Institute, Dana and David Dornsife School of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California (V.K., R.C.S.); and Chinese Academy of Sciences Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China (B.W., Q.Z.)
| | - Evgeny Kiselev
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (K.A.J., S.P., Z.-G.G., E.K.); The Bridge Institute, Dana and David Dornsife School of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California (V.K., R.C.S.); and Chinese Academy of Sciences Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China (B.W., Q.Z.)
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9
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Chang H, Yanachkov IB, Dix EJ, Yanachkova M, Li Y, Barnard MR, Wright GE, Michelson AD, Frelinger AL. Antiplatelet activity, P2Y₁ and P2Y₁₂ inhibition, and metabolism in plasma of stereoisomers of diadenosine 5',5'″-P¹ ,P⁴-dithio-P²,P³-chloromethylenetetraphosphate. PLoS One 2014; 9:e94780. [PMID: 24722456 PMCID: PMC3983250 DOI: 10.1371/journal.pone.0094780] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 03/19/2014] [Indexed: 12/18/2022] Open
Abstract
Background Diadenosine tetraphosphate (Ap4A), a constituent of platelet dense granules, and its P1,P4-dithio and/or P2,P3-chloromethylene analogs, inhibit adenosine diphosphate (ADP)-induced platelet aggregation. We recently reported that these compounds antagonize both platelet ADP receptors, P2Y1 and P2Y12. The most active of those analogs, diadenosine 5′,5″″-P1,P4-dithio-P2,P3-chloromethylenetetraphosphate, (compound 1), exists as a mixture of 4 stereoisomers. Objective To separate the stereoisomers of compound 1 and determine their effects on platelet aggregation, platelet P2Y1 and P2Y12 receptor antagonism, and their metabolism in human plasma. Methods We separated the 4 diastereomers of compound 1 by preparative reversed-phase chromatography, and studied their effect on ADP-induced platelet aggregation, P2Y1-mediated changes in cytosolic Ca2+, P2Y12-mediated changes in VASP phosphorylation, and metabolism in human plasma. Results The inhibition of ADP-induced human platelet aggregation and human platelet P2Y12 receptor, and stability in human plasma strongly depended on the stereo-configuration of the chiral P1- and P4-phosphorothioate groups, the SPSP diastereomer being the most potent inhibitor and completely resistant to degradation in plasma, and the RPRP diastereomer being the least potent inhibitor and with the lowest plasma stability. The inhibitory activity of SPRP diastereomers depended on the configuration of the pseudo-asymmetric carbon of the P2,P3-chloromethylene group, one of the configurations being significantly more active than the other. Their plasma stability did not differ significantly, being intermediate to that of the SPSP and the RPRP diastereomers. Conclusions The presently-described stereoisomers have utility for structural, mechanistic, and drug development studies of dual antagonists of platelet P2Y1 and P2Y12 receptors.
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Affiliation(s)
- Hung Chang
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Hematology Division, Chang Gung Memorial Hospital, Chang Gung University, Taipei, Taiwan
| | - Ivan B. Yanachkov
- GLSynthesis Inc., Worcester, Massachusetts, United States of America
| | - Edward J. Dix
- GLSynthesis Inc., Worcester, Massachusetts, United States of America
| | - Milka Yanachkova
- GLSynthesis Inc., Worcester, Massachusetts, United States of America
| | - YouFu Li
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Marc R. Barnard
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - George E. Wright
- GLSynthesis Inc., Worcester, Massachusetts, United States of America
| | - Alan D. Michelson
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Andrew L. Frelinger
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Begrow F, Verspohl EJ. Effect of Ap<sub>4</sub>A, UTP and Salbutamol on Mucociliary Clearance in a Mouse Model of Cystic Fibrosis (<i>in Situ</i>). ACTA ACUST UNITED AC 2013. [DOI: 10.4236/pp.2013.42025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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11
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Chang H, Yanachkov IB, Dix EJ, Li YF, Barnard MR, Wright GE, Michelson AD, Frelinger AL. Modified diadenosine tetraphosphates with dual specificity for P2Y1 and P2Y12 are potent antagonists of ADP-induced platelet activation. J Thromb Haemost 2012; 10:2573-80. [PMID: 23083103 PMCID: PMC5704993 DOI: 10.1111/jth.12035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Diadenosine 5',5'''-P(1),P(4)-tetraphosphate (Ap(4)A), a natural compound stored in platelet dense granules, inhibits ADP-induced platelet aggregation. Ap(4)A inhibits the platelet ADP receptors P2Y(1) and P2Y(12), is a partial agonist of P2Y(12), and is a full agonist of the platelet ATP-gated ion channel P2X1. Modification of the Ap(4)A tetraphosphate backbone enhances inhibition of ADP-induced platelet aggregation. However, the effects of these Ap(4)A analogs on human platelet P2Y(1), P2Y(12) and P2X1 are unclear. OBJECTIVE To determine the agonist and antagonist activities of diadenosine tetraphosphate analogs towards P2Y(1), P2Y(12), and P2X1. METHODS We synthesized the following Ap(4)A analogs: P(1),P(4)-dithiotetraphosphate; P(2),P(3)-chloromethylenetetraphosphate; P(1)-thio-P(2),P(3)-chloromethylenetetraphosphate; and P(1),P(4)-dithio-P(2),P(3)-chloromethylenetetraphosphate. We then measured the effects of these analogs on: (i) ADP-induced platelet aggregation; (ii) P2Y(1)-mediated changes in cytosolic Ca(2+); (iii) P2Y(12)-mediated changes in vasodilator-stimulated phosphoprotein phosphorylation; and (iv) P2X1-mediated entry of extracellular Ca(2+). RESULTS Ap(4)A analogs with modifications in the phosphate backbone inhibited both P2Y(1) and P2Y(12), and showed no agonist activity towards these receptors. The dithio modification increased inhibition of P2Y(1), P2Y(12), and platelet aggregation, whereas the chloromethylene modification increased inhibition of P2Y(12) and platelet aggregation, but decreased P2Y(1) inhibition. Combining the dithio and chloromethylene modifications increased P2Y(1) and P2Y(12) inhibition. As compared with Ap(4)A, each modification decreased agonist activity towards P2X1, and the dual modification completely eliminated P2X1 agonist activity. CONCLUSIONS As compared with Ap(4)A, tetraphosphate backbone analogs of Ap(4)A have diminished activity towards P2X1 but inhibit both P2Y(1) and P2Y(12) and, with greater potency, inhibit ADP-induced platelet aggregation. Thus, diadenosine tetraphosphate analogs with dual receptor selectivity may have potential as antiplatelet drugs.
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Affiliation(s)
- H Chang
- Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
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12
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Elliott TS, Slowey A, Ye Y, Conway SJ. The use of phosphate bioisosteres in medicinal chemistry and chemical biology. MEDCHEMCOMM 2012. [DOI: 10.1039/c2md20079a] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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13
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Purinergic receptor-mediated morphological changes in microglia are transient and independent from inflammatory cytokine release. Eur J Pharmacol 2010; 643:202-10. [PMID: 20621081 DOI: 10.1016/j.ejphar.2010.06.046] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 06/01/2010] [Accepted: 06/24/2010] [Indexed: 01/01/2023]
Abstract
Microglia are commonly described as existing in resting or active states based on morphology or level of cytokine production. Extracellular ATP is a physiologically-relevant activator of microglia, which express a number of purinergic receptors. As P2Y(12) has been linked to chemotaxis, we used a panel of purinergic compounds to understand the role of ATP receptors in morphological transformation and correlate this with TNFalpha production. We quantified activation of cultured microglia with LPS or purinergic receptor agonists by using automated image analysis of cell morphology and CD11b expression and correlated this with TNFalpha release measured by ELISA. Treatment with both ATP and the P2Y(12) receptor agonist, 2-methylthio adenosine diphosphate (2MeSADP), caused a transient increase in CD11b expression (EC(50)=1.2 microM and 187 nM, respectively) and a reduction in process count that reversed within 90 min later. These changes were not accompanied by the release of TNFalpha. Forskolin, IBMX, and pertussis toxin inhibited these changes, but the PLC inhibitor, U73122, did not. 2MeSAMP blocked the ATP response, while AP4A blocked the 2MeSADP response, implicating P2Y(12/13). Microglia activation by LPS also caused an increase in CD11b expression and a reduction in process count; however, in contrast to activation by ATP, morphological transformation was accompanied by a concentration-dependent increase in TNFalpha secretion These data demonstrate that morphological transformation and TNFalpha release are separable events mediated by different, or non-convergent pathways and that although ATP can initiate morphological changes, additional factors are required to maintain activation over sustained periods.
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14
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P2Y nucleotide receptors: promise of therapeutic applications. Drug Discov Today 2010; 15:570-8. [PMID: 20594935 DOI: 10.1016/j.drudis.2010.05.011] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 04/12/2010] [Accepted: 05/21/2010] [Indexed: 12/31/2022]
Abstract
Extracellular nucleotides, such as ATP and UTP, have distinct signaling roles through a class of G-protein-coupled receptors, termed P2Y. The receptor ligands are typically charged molecules of low bioavailability and stability in vivo. Recent progress in the development of selective agonists and antagonists for P2Y receptors and study of knockout mice have led to new drug concepts based on these receptors. The rapidly accelerating progress in this field has already resulted in drug candidates for cystic fibrosis, dry eye disease and thrombosis. On the horizon are novel treatments for cardiovascular diseases, inflammatory diseases and neurodegeneration.
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15
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Chang H, Yanachkov IB, Michelson AD, Li Y, Barnard MR, Wright GE, Frelinger AL. Agonist and antagonist effects of diadenosine tetraphosphate, a platelet dense granule constituent, on platelet P2Y1, P2Y12 and P2X1 receptors. Thromb Res 2009; 125:159-65. [PMID: 19945153 DOI: 10.1016/j.thromres.2009.11.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 09/30/2009] [Accepted: 11/05/2009] [Indexed: 10/20/2022]
Abstract
INTRODUCTION Diadenosine 5',5'''-P(1),P(4)- tetraphosphate (Ap(4)A) is stored in platelet dense granules, but its effects on platelet function are not well understood. METHODS AND RESULTS We examined the effects of Ap(4)A on platelet purinergic receptors P2Y(1), P2Y(12) and P2X(1). Flow cytometry was used to measure the effects of Ap(4)A in the presence or absence of ADP on: a) P2Y(12)-mediated decrease in intraplatelet phosphorylated vasodilator stimulated phosphoprotein (VASP), b) P2Y(1)-mediated increase in platelet cytosolic Ca(2+), and c) P2X(1)-mediated intraplatelet entry of extracellular Ca(2+). ADP-stimulated platelet shape change (P2Y(1)-mediated) and aggregation (P2Y(1)- and P2Y(12)-mediated) were measured optically. Ap(4)A inhibited 3 microM ADP-induced: a) platelet aggregation (IC(50) 9.8+/-2.8 microM), b) P2Y(1)-mediated shape change, c) P2Y(1)-mediated increase in platelet cytosolic Ca(2+) (IC(50) 40.8+/-12.3 microM), and d) P2Y(12)-mediated decrease in VASP phosphorylation (IC(50)>250 microM). In the absence of added ADP, Ap(4)A had agonist effects on platelet P2X(1) and P2Y(12), but not P2Y(1), receptors. CONCLUSION Ap(4)A, a constituent of platelet dense granules, is a) an antagonist of platelet P2Y(1) and P2Y(12) receptors, where it inhibits the effects of ADP, and b) an agonist of platelet P2X(1) and P2Y(12) receptors.
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Affiliation(s)
- Hung Chang
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
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16
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Menéndez-Arias L. Mechanisms of resistance to nucleoside analogue inhibitors of HIV-1 reverse transcriptase. Virus Res 2008; 134:124-46. [PMID: 18272247 DOI: 10.1016/j.virusres.2007.12.015] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 12/21/2007] [Accepted: 12/21/2007] [Indexed: 10/22/2022]
Abstract
Human immunodeficiency virus (HIV) reverse transcriptase (RT) inhibitors can be classified into nucleoside and nonnucleoside RT inhibitors. Nucleoside RT inhibitors are converted to active triphosphate analogues and incorporated into the DNA in RT-catalyzed reactions. They act as chain terminators blocking DNA synthesis, since they lack the 3'-OH group required for the phosphodiester bond formation. Unfortunately, available therapies do not completely suppress viral replication, and the emergence of drug-resistant HIV variants is facilitated by the high adaptation capacity of the virus. Mutations in the RT-coding region selected during treatment with nucleoside analogues confer resistance through different mechanisms: (i) altering discrimination between nucleoside RT inhibitors and natural substrates (dNTPs) (e.g. Q151M, M184V, etc.), or (ii) increasing the RT's phosphorolytic activity (e.g. M41L, T215Y and other thymidine analogue resistance mutations), which in the presence of a pyrophosphate donor (usually ATP) allow the removal of chain-terminating inhibitors from the 3' end of the primer. Both mechanisms are implicated in multi-drug resistance. The excision reaction can be modulated by mutations conferring resistance to nucleoside or nonnucleoside RT inhibitors, and by amino acid substitutions that interfere with the proper binding of the template-primer, including mutations that affect RNase H activity. New developments in the field should contribute towards improving the efficacy of current therapies.
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Affiliation(s)
- Luis Menéndez-Arias
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, c/Nicolás Cabrera, 1, Campus de Cantoblanco, 28049 Madrid, Spain.
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17
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Hourani SM, Hall DA. P2T purinoceptors: ADP receptors on platelets. CIBA FOUNDATION SYMPOSIUM 2007; 198:53-64; discussion 64-70. [PMID: 8879818 DOI: 10.1002/9780470514900.ch3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
ADP acts on platelets via the P2T purinoceptor to cause aggregation, but the way in which it does so is not fully understood. Most aggregating agents act via G protein-coupled receptors to stimulate phospholipase C (PLC) and so mobilize Ca2+ via inositol trisphosphate, whereas ADP clearly causes the mobilization of Ca2+ from internal stores but is only a weak activator of PLC. ADP also inhibits adenylate cyclase and it has been suggested that this effect is mediated by a different receptor, although evidence from antagonist studies argues against this. Studies of Ca2+ influx have shown that ADP is unique in causing a rapid influx of Ca2+, and patch-clamp studies have confirmed the activation by ADP of non-selective cation channels. This would imply the existence of two ADP receptors on platelets, a receptor-operated channel responsible for the rapid Ca2+ influx and a G protein-coupled receptor possibly linked to both inhibition of adenylate cyclase and mobilization of Ca2+. In this review the structure-activity relationships for aggregation, inhibition of adenylate cyclase and increases in cytoplasmic Ca2+ are summarized, and the relationship between these effects discussed.
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Affiliation(s)
- S M Hourani
- Receptors and Cellular Regulation Research Group, School of Biological Sciences, University of Surrey, Guildford, UK
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18
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Romanenko VD, Kukhar VP. Fluorinated phosphonates: synthesis and biomedical application. Chem Rev 2007; 106:3868-935. [PMID: 16967924 DOI: 10.1021/cr051000q] [Citation(s) in RCA: 287] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Vadim D Romanenko
- Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of the Ukraine, 1 Murmanska Street, Kyiv-94 02660, Ukraine
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19
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Abbracchio MP, Burnstock G, Boeynaems JM, Barnard EA, Boyer JL, Kennedy C, Knight GE, Fumagalli M, Gachet C, Jacobson KA, Weisman GA. International Union of Pharmacology LVIII: update on the P2Y G protein-coupled nucleotide receptors: from molecular mechanisms and pathophysiology to therapy. Pharmacol Rev 2006; 58:281-341. [PMID: 16968944 PMCID: PMC3471216 DOI: 10.1124/pr.58.3.3] [Citation(s) in RCA: 974] [Impact Index Per Article: 54.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
There have been many advances in our knowledge about different aspects of P2Y receptor signaling since the last review published by our International Union of Pharmacology subcommittee. More receptor subtypes have been cloned and characterized and most orphan receptors de-orphanized, so that it is now possible to provide a basis for a future subdivision of P2Y receptor subtypes. More is known about the functional elements of the P2Y receptor molecules and the signaling pathways involved, including interactions with ion channels. There have been substantial developments in the design of selective agonists and antagonists to some of the P2Y receptor subtypes. There are new findings about the mechanisms underlying nucleotide release and ectoenzymatic nucleotide breakdown. Interactions between P2Y receptors and receptors to other signaling molecules have been explored as well as P2Y-mediated control of gene transcription. The distribution and roles of P2Y receptor subtypes in many different cell types are better understood and P2Y receptor-related compounds are being explored for therapeutic purposes. These and other advances are discussed in the present review.
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Affiliation(s)
- Maria P Abbracchio
- Department of Pharmacological Sciences, University of Milan, Milan, Italy
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20
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Elmaleh DR, Fischman AJ, Tawakol A, Zhu A, Shoup TM, Hoffmann U, Brownell AL, Zamecnik PC. Detection of inflamed atherosclerotic lesions with diadenosine-5',5'''-P1,P4-tetraphosphate (Ap4A) and positron-emission tomography. Proc Natl Acad Sci U S A 2006; 103:15992-6. [PMID: 17038498 PMCID: PMC1599947 DOI: 10.1073/pnas.0607246103] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Diadenosine-5',5'''-P(1),P(4)-tetraphosphate (Ap(4)A) and its analog P(2),P(3)-monochloromethylene diadenosine-5',5'''-P(1),P(4)-tetraphosphate (AppCHClppA) are competitive inhibitors of adenosine diphosphate-induced platelet aggregation, which plays a central role in arterial thrombosis and plaque formation. In this study, we evaluate the imaging capabilities of positron-emission tomography (PET) with P(2),P(3)-[(18)F]monofluoromethylene diadenosine-5',5'''-P(1),P(4)-tetraphosphate ([(18)F]AppCHFppA) to detect atherosclerotic lesions in male New Zealand White rabbits. Three to six months after balloon injury to the aorta, the rabbits were injected with [(18)F]AppCHFppA, and microPET imaging showed rapid accumulation of this radiopharmaceutical in the atherosclerotic abdominal aorta, with lesions clearly visible 30 min after injection. Computed tomographic images were coregistered with PET images to improve delineation of aortoiliac tracer activity. Plaque macrophage density, quantified by immunostaining with RAM11 against rabbit macrophages, correlated with PET measurements of [(18)F]AppCHFppA uptake (r = 0.87, P < 0.0001), whereas smooth-muscle cell density, quantified by immunostaining with 1A4 against smooth muscle actin, did not. Biodistribution studies of [(18)F]AppCHFppA in normal rats indicated typical adenosine dinucleotide behavior with insignificant myocardial uptake and fast kidney clearance. The accumulation of [(18)F]AppCHFppA in macrophage-rich atherosclerotic plaques can be quantified noninvasively with PET. Hence, [(18)F]AppCHFppA holds promise for the noninvasive characterization of vascular inflammation.
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Affiliation(s)
- D R Elmaleh
- Department of Radiology and Cardiology Division, Massachusetts General Hospital, Boston, MA 02114, USA.
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21
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Nahum V, Tulapurkar M, Lévesque SA, Sévigny J, Reiser G, Fischer B. Diadenosine and diuridine poly(borano)phosphate analogues: synthesis, chemical and enzymatic stability, and activity at P2Y1 and P2Y2 receptors. J Med Chem 2006; 49:1980-90. [PMID: 16539385 DOI: 10.1021/jm050955y] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dinucleoside polyphosphates, NpnN', exert their physiological effects via P2 receptors. They are attractive drug targets as they offer better stability and specificity compared to nucleotides, the most common P2-receptor ligands. To further improve the properties of NpnN', which are still pharmacologically unsatisfactory, we developed novel boranophosphate isosteres of dinucleoside polyphosphates, denoted as Npn(B)N. These analogues were obtained in a facile and efficient synthesis as the exclusive products in a concerted reaction of two nucleoside phosphorimidazolides and inorganic boranophosphate. This unusual reaction is due to the preorganization of three reactant molecules by the Mg2+ ion. We found that Ap3/5(beta/gamma-B)A analogues were potent P2Y1-R agonists. Ap5(gamma-B)A was equipotent to 2-MeS-ADP (EC50 6.3x10(-8) M), thus making it one of the most potent P2Y1-R agonists currently known. Moreover, Ap5(gamma-B)A did not activate P2Y2-R. In contrast, Up3/5(beta/gamma-B)U analogues were extremely poor agonists of both P2Y1-R and P2Y2-R. Npn(B)N analogues exhibited remarkable chemical stability under physiological conditions. Under conditions mimicking gastric juice, Np3(beta-B)N analogues exhibited a half-life (t1/2) of 1.3 h, whereas Np5(gamma-B)N degraded at a much faster rate (t1/2 18 min). The hydrolysis of Ap3(beta-B)A by human nucleotide pyrophosphatase phosphodiesterases (NPP1 and NPP3) was slowed by 40% and 59%, respectively, as compared to Ap3A. However, this effect of the boranophosphate was position-dependent, as Np5(gamma-B)N was degraded at a rate comparable to that of Np5N. In summary, Ap5(gamma-B)A appears to be a highly potent and selective P2Y1-R agonist, as compared to the parent compound. This promising scaffold will be applied in the design of future metabolically stable analogues.
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Affiliation(s)
- Victoria Nahum
- Department of Chemistry, Gonda-Goldschmied Medical Research Center, Bar-Ilan University, Ramat-Gan 52900, Israel
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Jacobson KA, Mamedova L, Joshi BV, Besada P, Costanzi S. Molecular recognition at adenine nucleotide (P2) receptors in platelets. Semin Thromb Hemost 2005; 31:205-16. [PMID: 15852224 PMCID: PMC4423562 DOI: 10.1055/s-2005-869526] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Transmembrane signaling through P2Y receptors for extracellular nucleotides controls a diverse array of cellular processes, including thrombosis. Selective agonists and antagonists of the two P2Y receptors present on the platelet surface-the G (q)-coupled P2Y (1) subtype and the G (i)-coupled P2Y (12) subtype-are now known. High-affinity antagonists of each have been developed from nucleotide structures. The (N)-methanocarba bisphosphate derivatives MRS2279 and MRS2500 are potent and selective P2Y (1) receptor antagonists. The carbocyclic nucleoside AZD6140 is an uncharged, orally active P2Y (12) receptor antagonist of nM affinity. Another nucleotide receptor on the platelet surface, the P2X (1) receptor, the activation of which may also be proaggregatory, especially under conditions of high shear stress, has high-affinity ligands, although high selectivity has not yet been achieved. Although alpha,beta-methylene-adenosine triphosphate (ATP) is the classic agonist for the P2X (1) receptor, where it causes rapid desensitization, the agonist BzATP is among the most potent in activating this subtype. The aromatic sulfonates NF279 and NF449 are potent antagonists of the P2X (1) receptor. The structures of the two platelet P2Y receptors have been modeled, based on a rhodopsin template, to explain the basis for nucleotide recognition within the putative transmembrane binding sites. The P2Y (1) receptor model, especially, has been exploited in the design and optimization of antagonists targeted to interact selectively with that subtype.
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Affiliation(s)
- Kenneth A Jacobson
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0810, USA.
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Shaver SR, Rideout JL, Pendergast W, Douglass JG, Brown EG, Boyer JL, Patel RI, Redick CC, Jones AC, Picher M, Yerxa BR. Structure-activity relationships of dinucleotides: Potent and selective agonists of P2Y receptors. Purinergic Signal 2005; 1:183-91. [PMID: 18404503 PMCID: PMC2096529 DOI: 10.1007/s11302-005-0648-2] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 11/12/2004] [Indexed: 11/25/2022] Open
Abstract
Dinucleoside polyphosphates act as agonists on purinergic P2Y receptors to mediate a variety of cellular processes. Symmetrical, naturally occurring purine dinucleotides are found in most living cells and their actions are generally known. Unsymmetrical purine dinucleotides and all pyrimidine containing dinucleotides, however, are not as common and therefore their actions are not well understood. To carry out a thorough examination of the activities and specificities of these dinucleotides, a robust method of synthesis was developed to allow manipulation of either nucleoside of the dinucleotide as well as the phosphate chain lengths. Adenosine containing dinucleotides exhibit some level of activity on P2Y1 while uridine containing dinucleotides have some level of agonist response on P2Y2 and P2Y6. The length of the linking phosphate chain determines a different specificity; diphosphates are most accurately mimicked by dinucleoside triphosphates and triphosphates most resemble dinucleoside tetraphosphates. The pharmacological activities and relative metabolic stabilities of these dinucleotides are reported with their potential therapeutic applications being discussed.
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Affiliation(s)
- Sammy R Shaver
- Inspire, 4222 Emperor Boulevard, Suite 470, Durham, NC, 27703, USA,
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Pojoga LH, Haghiac ML, Moose JE, Hilderman RH. Determination of ATP impurity in adenine dinucleotides. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2004; 23:581-98. [PMID: 15113025 DOI: 10.1081/ncn-120030716] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Adenine dinucleotides (ApnA) are extracellular signal molecules that are released from blood platelets, following stress, into the vascular system. The most abundant and best-characterized ApnA (Ap4A) interacts with a unique receptor on bovine aortic endothelial cells (BAEC) where it induces nitric oxide. Ap4A also interacts with P2 purinoceptors on BAEC to modulate Ca2+ mobilization and prostacyclin release; this behavior can be equally well explained by Ap4A being either a partial agonist to these receptors, or an antagonist in the presence of ATP contamination. To discern between these two possibilities, we have investigated the presence of such contaminants in ApnA preparations. The studies herein indicate that ApnAs (n = 3-6) contain ATP impurities; thus, when characterizing the ApnA interaction with ATP-binding sites, investigators must assure that the response elicited is not partly due to an ATP impurity. We here provide a means for detecting and estimating ATP impurities within Ap4A preparations while also eliminating them; the level of this contamination is estimated to be as low as 0.2%. We applied our method to distinguish the true effect of Ap4A at P2 purinoceptors; our findings are consistent with Ap4A acting as a partial agonist to these receptors. We also applied our method to characterizing the ApnA interaction with luciferase, and found that decontaminated ApnA (n = 4-6) are weak substrates for luciferase.
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Affiliation(s)
- Luminita H Pojoga
- Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina 29634-0324, USA
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Vollmayer P, Clair T, Goding JW, Sano K, Servos J, Zimmermann H. Hydrolysis of diadenosine polyphosphates by nucleotide pyrophosphatases/phosphodiesterases. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:2971-8. [PMID: 12846830 DOI: 10.1046/j.1432-1033.2003.03674.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Diadenosine polyphosphates (ApnAs) act as extracellular signaling molecules in a broad variety of tissues. They were shown to be hydrolyzed by surface-located enzymes in an asymmetric manner, generating AMP and Apn-1 from ApnA. The molecular identity of the enzymes responsible remains unclear. We analyzed the potential of NPP1, NPP2, and NPP3, the three members of the ecto-nucleotide pyrophosphatase/phosphodiesterase family, to hydrolyze the diadenosine polyphosphates diadenosine 5',5"'-P1,P3-triphosphate (Ap3A), diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A), and diadenosine 5',5"'-P1,P5-pentaphosphate, (Ap5A), and the diguanosine polyphosphate, diguanosine 5',5"'-P1,P4-tetraphosphate (Gp4G). Each of the three enzymes hydrolyzed Ap3A, Ap4A, and Ap5A at comparable rates. Gp4G was hydrolyzed by NPP1 and NPP2 at rates similar to Ap4A, but only at half this rate by NPP3. Hydrolysis was asymmetric, involving the alpha,beta-pyrophosphate bond. ApnA hydrolysis had a very alkaline pH optimum and was inhibited by EDTA. Michaelis constant (Km) values for Ap3A were 5.1 micro m, 8.0 micro m, and 49.5 micro m for NPP1, NPP2, and NPP3, respectively. Our results suggest that NPP1, NPP2, and NPP3 are major enzyme candidates for the hydrolysis of extracellular diadenosine polyphosphates in vertebrate tissues.
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Affiliation(s)
- Petra Vollmayer
- AK Neurochemie, Biozentrum der J. W. Goethe-Universitaet, Frankfurt am Main, Germany
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Marteau F, Le Poul E, Communi D, Communi D, Labouret C, Savi P, Boeynaems JM, Gonzalez NS. Pharmacological characterization of the human P2Y13 receptor. Mol Pharmacol 2003; 64:104-12. [PMID: 12815166 DOI: 10.1124/mol.64.1.104] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The P2Y13 receptor has recently been identified as a new P2Y receptor sharing a high sequence homology with the P2Y12 receptor as well as similar functional properties: coupling to Gi and responsiveness to ADP (Communi et al., 2001). In the present study, the pharmacology of the P2Y13 receptor and its differences with that of the P2Y12 receptor have been further characterized in 1321N1 cells (binding of [33P]2-methylthio-ADP (2MeSADP) and of GTPgamma[35S]), 1321N1 cells coexpressing Galpha16 [AG32 cells: inositol trisphosphate (IP3) measurement, binding of GTPgamma[35S]) and Chinese hamster ovary (CHO)-K1 cells (cAMP assay)]. 2MeSADP was more potent than ADP in displacing [33P]2MeSADP bound to 1321N1 cells and increasing GTPgamma[35S] binding to membranes prepared from the same cells. Similarly, 2MeSADP was more potent than ADP in stimulating IP3 accumulation after 10 min in AG32 cells and increasing cAMP in pertussis toxin-treated CHO-K1 cells stimulated by forskolin. On the other hand, ADP and 2MeSADP were equipotent at stimulating IP3 formation in AG32 cells after 30 s and inhibiting forskolininduced cAMP accumulation in CHO-K1 cells. These differences in potency cannot be explained by differences in degradation rate, which in AG32 cells was similar for the two nucleotides. When contaminating diphosphates were enzymatically removed and assay of IP3 was performed after 30 s, ATP and 2MeSATP seemed to be weak partial agonists of the P2Y13 receptor expressed in AG32 cells. The stimulatory effect of ADP on the P2Y13 receptor in AG32 cells was antagonized by reactive blue 2, suramin, pyridoxal-phosphate-6-azophenyl-2',4'disulfonic acid, diadenosine tetraphosphate, and 2-(propylthio)-5'-adenylic acid, monoanhydride with dichloromethylenebis (phosphonic acid) (AR-C67085MX), but not by N6-methyl 2'-deoxyadenosine 3',5'-bisphosphate (MRS-2179) (up to 100 microM). The most potent antagonist was N6-(2-methylthioethyl)-2-(3,3,3-trifluoropropylthio)-5'-adenylic acid, monoanhydride with dichloromethylenebis (phosphonic acid) (ARC69931MX) (IC50 = 4 nM), which behaved in a noncompetitive way. The active metabolite of clopidogrel was unable to displace bound 2MeSADP at concentrations up to 2 microM.
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Affiliation(s)
- Frederic Marteau
- Institute for Interdisciplinary Research, School of Medicine, and Department of Medical Chemistry, Erasme Hospital, Brussels, Belgium.
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Walkowiak B, Baraniak J, Cierniewski CS, Stec W. Inhibition of ADP-triggered blood platelet aggregation by diadenosine polyphosphate analogues. Bioorg Med Chem Lett 2002; 12:1959-62. [PMID: 12113818 DOI: 10.1016/s0960-894x(02)00318-9] [Citation(s) in RCA: 8] [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
The synthesis and biological evaluation of new diadenosine polyphosphate analogues on blood platelet aggregation are reported. The most active are compounds with a sulfur atom replacing one or both non-bridging oxygens at phosphorus bound to adenosyl residues and hydroxymethyl groups of bis(hydroxymethyl)phosphinic acid.
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Affiliation(s)
- Bogdan Walkowiak
- Department of Molecular and Medical Biophysics, Institute of Physiology and Biochemistry, Medical University of Lodz, Poland.
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Haghiac M, Pojoga LH, Hilderman RH. Studies on the effect of diadenlyated nucleotides on calcium mobilization and prostacyclin synthesis in bovine aortic endothelial cells. Cell Signal 2001; 13:145-50. [PMID: 11257460 DOI: 10.1016/s0898-6568(00)00147-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Extracellular adenine dinucleotides are modulators of blood vessel tone. We have previously demonstrated that Ap(2)A and Ap(4)A induce the synthesis of nitric oxide (NO) from bovine aortic endothelial cells (BAEC) while Ap(3)A and Ap(5)A do not [FEBS Lett. 427 (1998) 320; Arch. Biochem. Biophys. 364 (1999) 280.]. In this communication we determine the effect of Ap(x)As (x=2-5) on prostacyclin (PGI(2)) synthesis and Ca(2+) mobilization in BAEC. Ap(2)A and Ap(4)A significantly enhanced the synthesis of PGI(2) while Ap(3)A and Ap(5)A do not. These data support the notion that Ap(2)A and Ap(4)A are vasodilators. All four dinucleotides significantly enhanced Ca(2+) mobilization over basal levels. Ap(5)A and Ap(3)A enhanced 2.0 and 1.6 times more Ca(2+) release than Ap(4)A, respectively. Since neither Ap(5)A nor Ap(3)A enhanced the synthesis of either PGI(2) or NO but did mobilize Ca(2+), these data support the hypothesis that in BAEC Ca(2+) release is localized or compartmentalized.
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Affiliation(s)
- M Haghiac
- Department of Biological Sciences, Clemson University, Clemson, SC 29634-1903, USA
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Cooper HM, Rosenberg CR, Hilderman RH. p(1),p(4)-diadenosine 5'-tetraphosphate induces the uptake of arginine and citrulline by a pore on the plasma membrane of bovine aortic endothelial cells. FEBS Lett 2000; 485:57-61. [PMID: 11086165 DOI: 10.1016/s0014-5793(00)02187-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We have previously demonstrated that p(1),p(4)-diadenosine 5'-tetraphosphate (Ap(4)A) induces the release of nitric oxide (NO) and modulates the uptake of extracellular L-arginine (L-Arg) and L-citrulline (L-Cit) by bovine aortic endothelial cells (BAEC) [Hilderman, R.H. and Christensen, E.F. (1998) FEBS Lett. 427, 320-324 and Hilderman, R.H., Casey, T.E. and Pojoga, L.H. (2000) Arch. Biochem. Biophys. 375, 124-130]. In this communication we report that extracellular Ap(4)A enhances the uptake of L-Arg and L-Cit through a pore on the plasma membrane of BAEC that is selective for these two amino acids. We also demonstrate that Ap(2)A, which induces NO release, enhances L-Arg uptake while Ap(5)A, a vasoconstrictor, does not enhance the uptake of L-Arg. The potential physiological significance of the uptake of these two amino acids in relation to NO synthesis is discussed.
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Affiliation(s)
- H M Cooper
- Department of Biomedical Sciences, Clemson University, SC 29634-1903, USA
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30
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Hilderman RH, Casey TE, Pojoga LH. P(1),P(4)-Diadenosine 5'-tetraphosphate modulates l-arginine and l-citrulline uptake by bovine aortic endothelial cells. Arch Biochem Biophys 2000; 375:124-30. [PMID: 10683257 DOI: 10.1006/abbi.1999.1643] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously demonstrated that P(1),P(4)-diadenosine 5'-tetraphosphate (Ap(4)A) interacts with high-affinity and low-affinity binding sites on the bovine aortic endothelial cell (BAEC) surface. In this report we demonstrate that Ap(4)A interaction with the lower affinity site modulates l-arginine (l-Arg) and l-citrulline (l-Cit) uptake by BAEC. Competition uptake studies demonstrate that l-Arg and l-Cit uptake occurs through a common transporter system that is sensitive to Ap(4)A. Evidence is also presented that is consistent with Ap(4)A modulating l-Arg uptake by increasing the affinity of l-Arg for the transporter.
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Affiliation(s)
- R H Hilderman
- Department of Microbiology, Clemson University, Clemson, South Carolina, 29634-1903, USA.
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Campbell SA, Kemerling AJ, Hilderman RH. Characterization of P1,P4-diadenosine 5'-tetraphosphate binding on bovine aortic endothelial cells. Arch Biochem Biophys 1999; 364:280-5. [PMID: 10190985 DOI: 10.1006/abbi.1999.1128] [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: 11/22/2022]
Abstract
In recent years it has become increasingly clear that alpha, omega-dinucleotides act as extracellular modulators of various biological processes. P1,P4-diadenosine 5'-tetraphosphate (Ap4A) is the best characterized alpha,omega-dinucleotides and acts as an extracellular signal molecule by inducing the release of nitric oxide (NO) from bovine aortic endothelial cells (BAEC) (R. H. Hilderman, and E. F. Christensen (1998) FEBS Lett. 407, 320-324). However, the characteristics of Ap4A binding to endothelial cells have not been determined. In this report we demonstrate that Ap4A binds to a heterogeneous population of receptors on BAEC. Competition ligand-binding studies using various adenosine dinucleotides, guanosine dinucleotides, adenosine/guanosine dinucleotides, and synthetic P2 purinoceptor agonists and antagonists demonstrate that Ap4A binds to a receptor on BAEC that has a high affinity for some of the adenosine dinucleotides. The apparent IC50 values for Ap4A, Ap2A, and Ap3A are between 12 and 15 microM, while the apparent IC50 values for Ap5A and Ap6A are greater than 500 microM. Evidence is also presented which suggests that this receptor can be classified as a putative P4 purinoceptor. Competition studies also demonstrate that Ap4A binds at a lower affinity to a second class of binding sites.
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Affiliation(s)
- S A Campbell
- Biological Sciences, Clemson University, Clemson, South Carolina, 29634-1903, USA
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32
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Ziganshin AU, Ziganshina LE, Burnstock G. Rate of diadenosine polyphosphate degradation by various guinea pig tissues. Bull Exp Biol Med 1999. [DOI: 10.1007/bf02433111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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33
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Blouse GE, Liu G, Hilderman RH. Characterization of ATP and P2 agonists binding to the cardiac plasma membrane P1,P4-diadenosine 5'-tetraphosphate receptor. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1375:61-72. [PMID: 9767112 DOI: 10.1016/s0005-2736(98)00140-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
P1,P4-Diadenosine 5'-tetraphosphate (Ap4A) acts as an extracellular modulator through its interaction with purinoceptors. Our laboratory has demonstrated the presence of an Ap4A receptor in cardiac tissue [1,2]. Due to the rapid hydrolysis of ATP by cardiac membranes the relationship of ATP and Ap4A binding to purinoceptors on cardiac membranes has not been characterized. In this communication we used two approaches to determine the relationship of ATP to the Ap4A receptor. Radioligand binding carried out with [alpha-32P]Ap4A and adenosine 5'-O-¿3-thiotriphosphate¿ ([gamma-35S]ATPgammaS) demonstrates the presence of a single high affinity binding site for Ap4A and the presence of two binding sites for ATPgammaS. The second approach utilized immunoaffinity purified Ap4A receptor that was shown to be free of ATPase and Ap4Aase activities. Non-radiolabeled Ap4A and ATPgammaS effectively inhibited photocrosslinking of [alpha-32P]8-N3Ap4A to the receptor polypeptide while ATP was a much less effective inhibitor. Furthermore, on plasma membranes [alpha-32P]8-N3Ap4A photocrosslinked to only a 50 kDa polypeptide. These data are consistent with Ap4A interacting with a homogeneous population of receptors on cardiac plasma membranes but with ATP having a low affinity for the receptor.
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Affiliation(s)
- G E Blouse
- Department of Biochemical Research, Henry Ford Health System, Detroit, MI 48202-2689, USA
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Hilderman RH, Christensen EF. P1,P4-diadenosine 5' tetraphosphate induces nitric oxide release from bovine aortic endothelial cells. FEBS Lett 1998; 427:320-4. [PMID: 9637249 DOI: 10.1016/s0014-5793(98)00454-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Since the infusion of P1,P4-diadenosine 5' tetraphosphate (Ap4A) into animal models induces vasodilation [1,2], the present study was performed to determine whether Ap4A induces the release of nitric oxide (NO) from endothelial cells. Ap4A induced NO release was 4.2-fold greater than the amount of NO released under basal condition. Ap4A induced NO release was inhibited by NG-nitro-L-arginine (L-NNA) and this inhibition was reversed by L-Arg. In addition, EGTA inhibits Ap4A induced NO release. These data are consistent with Ap4A inducing the release of NO from endothelial cells through the activation of endothelial nitric oxide synthase.
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Affiliation(s)
- R H Hilderman
- Department of Microbiology/Molecular Medicine, Greenville Hospital System/Clemson University Biomedical Cooperative, SC 29634-1903, USA.
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35
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Kisselev LL, Justesen J, Wolfson AD, Frolova LY. Diadenosine oligophosphates (Ap(n)A), a novel class of signalling molecules? FEBS Lett 1998; 427:157-63. [PMID: 9607303 DOI: 10.1016/s0014-5793(98)00420-7] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The diadenosine oligophosphates (Ap(n)A) were discovered in the mid-sixties in the course of studies on aminoacyl-tRNA synthetases (aaRS). Now, more than 30 years later, about 300 papers have been published around these substances in attempt to decipher their role in cells. Recently, Ap(n)A have emerged as intracellular and extracellular signalling molecules implicated in the maintenance and regulation of vital cellular functions and become considered as second messengers. Great variety of physiological and pathological effects in mammalian cells was found to be associated with alterations of Ap(n)A levels (n from 2 to 6) and Ap3A/Ap4A ratio. Cell differentiation and apoptosis have substantial and opposite effects on Ap3A/Ap4A ratio in cultured cells. A human Ap3A hydrolase, Fhit, appeared to be involved in protection of cells against tumourigenesis. Ap3A is synthesised by mammalian u synthetase (TrpRS) which in contrast to most other aaRS is unable to synthesise Ap4A and is an interferon-inducible protein. Moreover, Ap3A appeared to be a preferred substrate for 2-5A synthetase, also interferon-inducible, priming the synthesis of 2' adenylated derivatives of Ap3A, which in turn may serve as substrates of Fhit. Tumour suppressor activity of Fhit is assumed to be associated with involvement of the Fhit.Ap3A complex in cytokine signalling pathway(s) controlling cell proliferation. The Ap(n)A family is potentially a novel class of signal-transducing molecules whose functions are yet to be determined.
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Elmaleh DR, Narula J, Babich JW, Petrov A, Fischman AJ, Khaw BA, Rapaport E, Zamecnik PC. Rapid noninvasive detection of experimental atherosclerotic lesions with novel 99mTc-labeled diadenosine tetraphosphates. Proc Natl Acad Sci U S A 1998; 95:691-5. [PMID: 9435254 PMCID: PMC18482 DOI: 10.1073/pnas.95.2.691] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The development of a noninvasive imaging procedure for identifying atherosclerotic lesions is extremely important for the clinical management of patients with coronary artery and peripheral vascular disease. Although numerous radiopharmaceuticals have been proposed for this purpose, none has demonstrated the diagnostic accuracy required to replace invasive angiography. In this report, we used the radiolabeled purine analog, 99mTc diadenosine tetraphosphate (Ap4A; AppppA, P1,P4-di(adenosine-5')-tetraphosphate) and its analogue 99mTc AppCHClppA for imaging experimental atherosclerotic lesions in New Zealand White rabbits. Serial gamma camera images were obtained after intravenous injection of the radiolabeled dinucleotides. After acquiring the final images, the animals were sacrificed, ex vivo images of the aortas were recorded, and biodistribution was measured. 99mTc-Ap4A and 99mTc AppCHClppA accumulated rapidly in atherosclerotic abdominal aorta, and lesions were clearly visible within 30 min after injection in all animals that were studied. Both radiopharmaceuticals were retained in the lesions for 3 hr, and the peak lesion to normal vessel ratio was 7.4 to 1. Neither of the purine analogs showed significant accumulation in the abdominal aorta of normal (control) rabbits. The excised aortas showed lesion patterns that were highly correlated with the in vivo and ex vivo imaging results. The present study demonstrates that purine receptors are up-regulated in experimental atherosclerotic lesions and 99mTc-labeled purine analogs have potential for rapid noninvasive detection of plaque formation.
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Affiliation(s)
- D R Elmaleh
- Department of Radiology, Massachusetts General Hospital, Boston, USA
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37
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Maksel D, Guranowski A, Ilgoutz SC, Moir A, Blackburn MG, Gayler KR. Cloning and expression of diadenosine 5',5'''-P1,P4-tetraphosphate hydrolase from Lupinus angustifolius L. Biochem J 1998; 329 ( Pt 2):313-9. [PMID: 9425114 PMCID: PMC1219046 DOI: 10.1042/bj3290313] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The first isolation, cloning and expression of cDNA encoding an asymmetric diadenosine 5',5'''P1,P4-tetraphosphate pyrophosphohydrolase (Ap4A hydrolase) from a higher plant is described. Ap4A hydrolase protein was purified from seeds of both Lupinus luteus and Lupinus angustifolius and partially sequenced. The Ap4A hydrolase cDNA was cloned from L. angustifolius cotyledonary polyadenylated RNA using reverse transcription and PCR with primers based on the amino acid sequence. The cDNA encoded a protein of 199 amino acids, molecular mass 22982Da. When expressed in Escherichia coli fused to a maltose-binding protein, the enzyme catalysed asymmetric cleavage of Ap4A to AMP and ATP which was inhibited at concentrations of F- as low as 3 microM. These are properties characteristic of Ap4A hydrolase (asymmetrical) (EC 3.6.1. 17). Comparison of the Ap4A hydrolase sequences derived from the four known cDNAs from pig, human, lupin and fission yeast showed that, like the mammalian hydrolase, the lupin enzyme possesses a Mut T motif but no other significant similarities. No sequence similarity to the human fragile histidine triad protein, as found in the Ap4A hydrolase from Schizosaccharomyces pombe, was detected in the Ap4A hydrolase from lupin.
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Affiliation(s)
- D Maksel
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3052, Australia
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38
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Fenniri H, Hosseini MW, Lehn JM. Molecular Recognition of NADP(H) and ATP by Macrocyclic Polyamines Bearing Acridine Groups. Helv Chim Acta 1997. [DOI: 10.1002/hlca.19970800314] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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39
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Chan SW, Gallo SJ, Kim BK, Guo MJ, Blackburn GM, Zamecnik PC. P1,P4-dithio-P2,P3-monochloromethylene diadenosine 5',5'''-P1,P4-tetraphosphate: a novel antiplatelet agent. Proc Natl Acad Sci U S A 1997; 94:4034-9. [PMID: 9108100 PMCID: PMC20563 DOI: 10.1073/pnas.94.8.4034] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We have previously demonstrated in a series of searches for antithrombotic agents that diadenosine 5',5"'-P1,P4-tetraphosphate (AppppA) and its analogues are competitive inhibitors of ADP-induced platelet aggregation. Among various analogues, the P2,P3-monochloromethylene analog of AppppA (AppCHClppA) is superior to unmodified AppppA in its antiplatelet and antithrombotic effects. In this communication, we compare the antiplatelet potency of five newly synthesized agents with that of AppCHClppA. The five new agents include four diadenosine polyphosphate analogues [Ap(s)pCHClpp(s)A (p(s) indicates a thiophosphate), dAppCHClppdA, dAp,pCHClpp(s)dA, and AppCHClpCHClppA], and an adenosine tetraphosphate analogue (AppCHClpCHClp). When tested for their inhibitory effects on platelet aggregation by ADP, the most promising agent among them was Ap(s)pCHClpp(s)A. Both molecular and functional integrity of this compound proved to be stable in blood at 37 degrees C for at least 3 h. It also showed an excellent heat stability. This agent inhibits a number of aspects of ADP-induced platelet activation-e.g., release reaction, cytoplasmic calcium mobilization, thromboxane production, fibrinogen binding sites, and platelet factor 3 activity. Moreover, platelet aggregation induced by agonists other than ADP-e.g., arachidonic acid, collagen, and epinephrine-was inhibited partially by Ap(s)pCHClpp(s)A. It is concluded that (i) Ap(s)pCHClpp(s)A is a promising antiplatelet agent; (ii) it is resistant to blood phosphodiesterases and stable to heat treatment; (iii) platelet aggregation induced by collagen, epinephrine, or arachidonic acid is also inhibited in part by this agent; and (iv) specificity of the inhibitory effects is presented by unmodified adenosine moieties of the agent. Resistance to phosphodiesterases raises the possibility of oral administration.
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Affiliation(s)
- S W Chan
- Cypress Bioscience, Inc., Watertown, MA 02172, USA
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40
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Achievements and prospects in the creation of antiaggregative drugs (Review). Pharm Chem J 1997. [DOI: 10.1007/bf02464660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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41
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Edgecombe M, McLennan AG, Fisher MJ. Characterization of the binding of diadenosine 5',5'''-P1,P4-tetraphosphate (Ap4A) to rat liver cell membranes. Biochem J 1996; 314 ( Pt 2):687-93. [PMID: 8670086 PMCID: PMC1217101 DOI: 10.1042/bj3140687] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Diadenosine polyphosphates present in the extracellular environment can, through interaction with appropriate purinoceptors, influence a range of cellular activities. Here we have investigated the nature of the ligand:receptor interactions involved in diadenosine 5',5'''-P1, P4-tetraphosphate (Ap4A)-mediated stimulation of glycogen breakdown in isolated rat liver cells. [2-3H]Ap4A showed specific binding to both intact isolated liver cells and plasma membrane fractions prepared from isolated liver cells. HPLC analysis confirmed that binding was mediated by intact Ap4A and not by potential breakdown products (e.g. ATP, adenosine, etc.). Binding of [2-3H]Ap4A, to isolated liver cell plasma membrane preparations, was successfully displaced by a range of both naturally occurring and synthetic diadenosine polyphospates with the rank order potency Ap4A > or = Ap5A > Ap6A > Ap3A > Ap2A. [2-3H]Ap4A binding was not displaced by P1 effectors but was successfully displaced by a range of P2 effectors with the rank order potency 2-methylthio-ATP > ATP > ATP > or = adenosine 5'-[alpha beta-methylene]triphosphate > adenosine 5'-[beta gamma-methylene]triphospate. These findings are consistent with the interaction of Ap4A with a P2y-like subclass of purinoceptor and are discussed in relation to (1) the known purinoceptor populations in liver cell plasma membranes and (2) observations concerning the binding of diadenosine polyphosphates to purinoceptors in other tissues.
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Affiliation(s)
- M Edgecombe
- Department of Biochemistry, University of Liverpool, U.K
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42
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Chapter 3. P2 Purinoceptors: A Family of Novel Therapeutic Targets. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 1996. [DOI: 10.1016/s0065-7743(08)60442-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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43
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Theoclitou ME, Wittung EPL, Hindley AD, El-Thaher TSH, Miller AD. Characterisation of stress protein LysU. Enzymic synthesis of diadenosine 5′,5‴-P1,P4-tetraphosphate (Ap4A) analogues by LysU. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/p19960002009] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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44
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Theoclitou ME, El-Thaher TSH, Miller AD. Enzymatic synthesis of diadenosine 5′, 5‴-P1, P4-tetraphosphate (Ap4A) analogues by stress protein LysU. ACTA ACUST UNITED AC 1994. [DOI: 10.1039/c39940000659] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Walker J, Bossman P, Lackey BR, Zimmerman JK, Dimmick MA, Hilderman RH. The adenosine 5',5"',P1,P4-tetraphosphate receptor is at the cell surface of heart cells. Biochemistry 1993; 32:14009-14. [PMID: 8268179 DOI: 10.1021/bi00213a034] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have previously demonstrated the existence of an adenosine 5',5"',P1,P4-tetraphosphate (Ap4A) receptor in mouse hart membrane fractions [Hilderman, R. H., Martin, M., Zimmerman, J. K., & Pivorun, E. P. (1991) J. Biol. Chem. 266, 6915-6918]. However, we did not determine the cellular localization or distribution of the receptor. In this report, the Ap4A receptor is shown to be on the cell surface of individual mouse heart cells by the following four methods: (1) intact cells show specific, saturable, and reversible binding of Ap4A; (2) monoclonal antibodies (Mabs) raised against the Ap4A receptor inhibit Ap4A binding to its receptor on intact heart cells; (3) bound Mabs are shown to be at the outer cell surface via reaction with a alkaline phosphatase conjugated goat anti-rat IgG; (4) when intact cells are labeled with the impermeable cell surface labeling reagent, (sulfosuccinimido) biotin, labeled receptor is immunoprecipitated with Mabs. Furthermore, subcellular fractionation of mouse hearts demonstrates that virtually all of the Ap4A receptor is associated with a membrane fraction with at least 77% of the active receptor on plasma membranes.
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Affiliation(s)
- J Walker
- Department of Biological Sciences, Clemson University, South Carolina 29634-1903
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Pintor J, Díaz-Rey MA, Miras-Portugal MT. Ap4A and ADP-beta-S binding to P2 purinoceptors present on rat brain synaptic terminals. Br J Pharmacol 1993; 108:1094-9. [PMID: 8485620 PMCID: PMC1908170 DOI: 10.1111/j.1476-5381.1993.tb13510.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
1. Diadenosine tetraphosphate (Ap4A) a dinucleotide stored and released from rat brain synaptic terminals presents two types of affinity binding sites in synaptosomes. When [3H]-Ap4A was used for binding studies a Kd value of 0.10 +/- 0.014 nM and a Bmax value of 16.6 +/- 1.2 fmol mg-1 protein were obtained for the high affinity binding site from the Scatchard analysis. The second binding site, obtained by displacement studies, showed a Ki value of 0.57 +/- 0.09 microM. 2. Displacement of [3H]-Ap4A by non-labelled Ap4A and P2-purinoceptor ligands showed a displacement order of Ap4A > adenosine 5'-O-(2-thiodiphosphate) (ADP-beta-S) > 5'-adenylyl-imidodiphosphate (AMP-PNP) > alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-MeATP) in both sites revealed by the Ki values of 0.017 nM, 0.030 nM, 0.058 nM and 0.147 nM respectively for the high affinity binding site and values of 0.57 microM, 0.87 microM, 2.20 microM and 4.28 microM respectively for the second binding site. 3. Studies of the P2-purinoceptors present in synaptosomes were also performed with [35S]-ADP-beta-S. This radioligand showed two binding sites the first with Kd and Bmax values of 0.11 +/- 0.022 nM and 3.9 +/- 2.1 fmol mg-1 of protein respectively for the high affinity binding site obtained from the Scatchard plot. The second binding site showed a Ki of 0.018 +/- 0.0035 microM obtained from displacement curves. 4. Competition studies with diadenosine polyphosphates of [35S]-ADP-beta-S binding showed a displacement order of Ap4A > Ap5A > Ap6A in the high affinity binding site and Ki values of 0.023 nM, 0.081 nM and 5.72 nM respectively. The second binding site potency order was Ap5A> Ap4A > Ap6A,with Ki values of 0.28 microM, 0.53 microM and 5.32 microM respectively.5. Displacement studies of [35S]-ADP-beta-S with P2-purinoceptor agonists showed the following potency pattern: ADP-beta-S > AMP-PNP >alpha,beta-MeATP with Ki values of 0.021 nM, 0.029 nM 0.215 nM respectively in the high affinity binding site. 2-Methylthio-adenosine 5'-triphosphate (2MeSATP) was unable to displace [35S]-ADP-beta-S in this binding site. The second binding site showed a profile of ADP-beta-S> a,beta-MeATP> AMP-PNP > 2MeSATP and Ki values of 0.0 18 microM, 0.212 microM, 0.481 microM and 18.04 microM respectively.6. These studies suggest the presence of a new P2-purinoceptor in rat brain synaptosomes with high affinity for diadenosine polyphosphates which we tentatively designate as P2d.
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Affiliation(s)
- J Pintor
- Departamento Bioquímica, Universidad Complutense, Madrid, Spain
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Walker J, Hilderman RH. Identification of a serine protease which activates the mouse heart adenosine 5',5"',P1,P4-tetraphosphate receptor. Biochemistry 1993; 32:3119-23. [PMID: 8384488 DOI: 10.1021/bi00063a025] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have previously demonstrated that a serine protease dependent processing step is required for activation of the 30-kDa adenosine 5',5"',P1,P4-tetraphosphate (Ap4A) receptor. However, monoclonal antibodies (Mabs) against a 212-kDa polypeptide inhibit Ap4A binding to its receptor [Walker et al. (1993) Biochemistry 32, 1264-1269]. SDS-PAGE followed by autoradiography of [3H]diisopropylfluorophosphate (DIPF) covalently attached to membrane fractions reveals that the serine protease is the 212-kDa polypeptide or a proenzyme. Mabs against the 30-kDa Ap4A receptor are identified that inhibit Ap4A binding to its membrane receptor. These Mabs do not recognize the 212-kDa membrane protein but recognize four membrane proteins with molecular masses of 67, 55, 42, and 30 kDa. These data suggest that the precursor for the Ap4A receptor is a 67-kDa polypeptide which undergoes multiple cleavage events, at least one by the 212-kDa protein.
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Affiliation(s)
- J Walker
- Department of Biological Sciences, Clemson University, South Carolina 29634-1903
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Walker J, Lewis TE, Pivorun EP, Hilderman RH. Activation of the mouse heart adenosine 5',5"'-P1-P4-tetraphosphate receptor. Biochemistry 1993; 32:1264-9. [PMID: 8383527 DOI: 10.1021/bi00056a010] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have previously demonstrated that mouse brain membrane fractions have a specific, saturable receptor for diadenylated nucleotides. Binding is specific for two adenosines, and the length of the phosphate bridge is critical, with four phosphates being optimal [Hilderman et al. (1991) J. Biol. Chem. 266, 6915-6918]. In this report, we demonstrate that adenosine 5',5"'-P1,P4-tetraphosphate (Ap4A) binding to its receptor is dependent upon an activation step that requires divalent cations and a serine protease. Monoclonal antibodies (Mabs) are identified that inhibit Ap4A binding to its membrane receptor. These antibodies recognize a 212-kDa membrane protein. However, SDS-PAGE analysis of Ap4A cross-linked to membrane fractions reveals that Ap4A is not attached to the 212-kDa peptide but to a 30-kDa polypeptide. Appearance of the 30-kDa polypeptide is dependent on the activation step, and one of the inhibitory antibodies blocks its appearance. We suggest that the protease-dependent processing step involves cleavage of the 212-kDa component with the appearance of an active 30-kDa receptor.
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Affiliation(s)
- J Walker
- Department of Biological Sciences, Clemson University, South Carolina 29634-1903
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Kim BK, Zamecnik P, Taylor G, Guo MJ, Blackburn GM. Antithrombotic effect of beta,beta'-monochloromethylene diadenosine 5',5"'-P1,P4-tetraphosphate. Proc Natl Acad Sci U S A 1992; 89:11056-8. [PMID: 1438314 PMCID: PMC50482 DOI: 10.1073/pnas.89.22.11056] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The feasibility of using beta,beta'-monochloromethylene diadenosine 5',5"'-P1,P4-tetraphosphate (AppCHCl-ppA) as an antithrombotic agent was studied in a rabbit intracarotid cannula thrombosis model previously shown to be sensitive to antiplatelet agents. This analogue, having a P-C-P bridge in place of a P-O-P internucleoside linkage, has been found resistant to phosphodiesterase activity. Rabbits were infused with the dinucleotide at a dose of 50 mg per kg over a 2-hr period, at a controlled rate by pump. A 1-cm length of polyethylene cannula (1 mm i.d.) was tied into the carotid artery. Animals were stable under general anesthesia during the entire period of the experiment. In the control group, 16 of 20 animals formed clots, an incidence of 80%, whereas in the test animals, 6 of the 20 formed clots (30% incidence, P < 0.05). After preincubation of whole blood with 50 microM AppCHClppA at 37 degrees C for up to 3 hr, a consistent suppression of ADP-induced platelet aggregation was observed. The present study suggests that AppCHClppA may be useful as an antithrombotic agent in certain clinical situations, such as hemodialysis, arteriovenous shunts, and introduction of artificial heart valves. It may also possibly prevent extension of recent clots. The toxicity and metabolism of AppCHClppA have, however, yet to be explored.
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Affiliation(s)
- B K Kim
- Platelet Research Products, Inc., Watertown, MA 02171
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