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Paul DS, Blatt TN, Schug WJ, Clark EG, Kawano T, Mackman N, Murcia S, Poe KO, Mwiza JMN, Harden TK, Bergmeier W, Nicholas RA. Loss of P2Y 1 receptor desensitization does not impact hemostasis or thrombosis despite increased platelet reactivity in vitro. J Thromb Haemost 2023; 21:1891-1902. [PMID: 36958516 PMCID: PMC10809801 DOI: 10.1016/j.jtha.2023.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/20/2023] [Accepted: 03/09/2023] [Indexed: 03/25/2023]
Abstract
BACKGROUND The hemostatic plug formation at sites of vascular injury is strongly dependent on rapid platelet activation and integrin-mediated adhesion and aggregation. However, to prevent thrombotic complications, platelet aggregate formation must be a self-limiting process. The second-wave mediator adenosine diphosphate (ADP) activates platelets via Gq-coupled P2Y1 and Gi-coupled P2Y12 receptors. After ADP exposure, the P2Y1 receptor undergoes rapid phosphorylation-induced desensitization, a negative feedback mechanism believed to be critical for limiting thrombus growth. OBJECTIVE The objective of this study was to examine the role of rapid P2Y1 receptor desensitization on platelet function and thrombus formation in vivo. METHODS We analyzed a novel knock-in mouse strain expressing a P2Y1 receptor variant that cannot be phosphorylated beyond residue 340 (P2Y1340-0P), thereby preventing the desensitization of the receptor. RESULTS P2Y1340-0P mice followed a Mendelian inheritance pattern, and peripheral platelet counts were comparable between P2Y1340-0P/340-0P and control mice. In vitro, P2Y1340-0P/340-0P platelets were hyperreactive to ADP, showed a robust activation response to the P2Y1 receptor-selective agonist, MRS2365, and did not desensitize in response to repeated ADP challenge. We observed increased calcium mobilization, protein kinase C substrate phosphorylation, alpha granule release, activation of the small GTPase Rap1, and integrin inside-out activation/aggregation. This hyperreactivity, however, did not lead to increased platelet adhesion or excessive plug formation under physiological shear conditions. CONCLUSION Our studies demonstrate that receptor phosphorylation at the C-terminus is critical for P2Y1 receptor desensitization in platelets and that impaired desensitization leads to increased P2Y1 receptor signaling in vitro. Surprisingly, desensitization of the P2Y1 receptor is not required for limiting platelet adhesion/aggregation at sites of vascular injury, likely because ADP is degraded quickly or washed away in the bloodstream.
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Affiliation(s)
- David S Paul
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. https://twitter.com/David_S_Paul
| | - Tasha N Blatt
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Wyatt J Schug
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Emily G Clark
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Tomohiro Kawano
- UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Nigel Mackman
- UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sebastian Murcia
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kathryn O Poe
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jean Marie N Mwiza
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - T Kendall Harden
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Wolfgang Bergmeier
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Robert A Nicholas
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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2
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Molecular pharmacology of P2Y receptor subtypes. Biochem Pharmacol 2020; 187:114361. [PMID: 33309519 DOI: 10.1016/j.bcp.2020.114361] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/06/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023]
Abstract
Professor Geoffrey Burnstock proposed the concept of purinergic signaling via P1 and P2 receptors. P2Y receptors are G-protein-coupled receptors (GPCRs) for extracellular adenine and uracil nucleotides. Eight mammalian P2Y receptor subtypes have been identified. They are divided into two subgroups (P2Y1, P2Y2, P2Y4, P2Y6, and P2Y11) and (P2Y12, P2Y13, and P2Y14). P2Y receptors are found in almost all cells and mediate responses in physiology and pathophysiology including pain and inflammation. The antagonism of platelet P2Y12 receptors by cangrelor, ticagrelor or active metabolites of the thienopyridine compounds ticlopidine, clopidogrel and prasugrel reduces the ADP-induced platelet aggregation in patients with thrombotic complications of vascular diseases. The nucleotide agonist diquafosol acting at P2Y2 receptors is used for the treatment of the dry eye syndrome. Structural information obtained by crystallography of the human P2Y1 and P2Y12 receptor proteins, site-directed mutagenesis and molecular modeling will facilitate the rational design of novel selective drugs.
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3
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Thibeault PE, Ramachandran R. Biased signaling in platelet G-protein coupled receptors. Can J Physiol Pharmacol 2020; 99:255-269. [PMID: 32846106 DOI: 10.1139/cjpp-2020-0149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Platelets are small megakaryocyte-derived, anucleate, disk-like structures that play an outsized role in human health and disease. Both a decrease in the number of platelets and a variety of platelet function disorders result in petechiae or bleeding that can be life threatening. Conversely, the inappropriate activation of platelets, within diseased blood vessels, remains the leading cause of death and morbidity by affecting heart attacks and stroke. The fine balance of the platelet state in healthy individuals is controlled by a number of receptor-mediated signaling pathways that allow the platelet to rapidly respond and maintain haemostasis. G-protein coupled receptors (GPCRs) are particularly important regulators of platelet function. Here we focus on the major platelet-expressed GPCRs and discuss the roles of downstream signaling pathways (e.g., different G-protein subtypes or β-arrestin) in regulating the different phases of the platelet activation. Further, we consider the potential for selectively targeting signaling pathways that may contribute to platelet responses in disease through development of biased agonists. Such selective targeting of GPCR-mediated signaling pathways by drugs, often referred to as biased signaling, holds promise in delivering therapeutic interventions that do not present significant side effects, especially in finely balanced physiological systems such as platelet activation in haemostasis.
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Affiliation(s)
- Pierre E Thibeault
- Department of Physiology and Pharmacology, University of Western Ontario, 1151 Richmond Street, London, ON N6A5C1, Canada.,Department of Physiology and Pharmacology, University of Western Ontario, 1151 Richmond Street, London, ON N6A5C1, Canada
| | - Rithwik Ramachandran
- Department of Physiology and Pharmacology, University of Western Ontario, 1151 Richmond Street, London, ON N6A5C1, Canada.,Department of Physiology and Pharmacology, University of Western Ontario, 1151 Richmond Street, London, ON N6A5C1, Canada
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4
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Verweij EWE, Al Araaj B, Prabhata WR, Prihandoko R, Nijmeijer S, Tobin AB, Leurs R, Vischer HF. Differential Role of Serines and Threonines in Intracellular Loop 3 and C-Terminal Tail of the Histamine H 4 Receptor in β-Arrestin and G Protein-Coupled Receptor Kinase Interaction, Internalization, and Signaling. ACS Pharmacol Transl Sci 2020; 3:321-333. [PMID: 32296771 PMCID: PMC7155198 DOI: 10.1021/acsptsci.0c00008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Indexed: 12/24/2022]
Abstract
The histamine H4 receptor (H4R) activates Gαi-mediated signaling and recruits β-arrestin2 upon stimulation with histamine. β-Arrestins play a regulatory role in G protein-coupled receptor (GPCR) signaling by interacting with phosphorylated serine and threonine residues in the GPCR C-terminal tail and intracellular loop 3, resulting in receptor desensitization and internalization. Using bioluminescence resonance energy transfer (BRET)-based biosensors, we show that G protein-coupled receptor kinases (GRK) 2 and 3 are more quickly recruited to the H4R than β-arrestin1 and 2 upon agonist stimulation, whereas receptor internalization dynamics toward early endosomes was slower. Alanine-substitution revealed that a serine cluster at the distal end of the H4R C-terminal tail is essential for the recruitment of β-arrestin1/2, and consequently, receptor internalization and desensitization of G protein-driven extracellular-signal-regulated kinase (ERK)1/2 phosphorylation and label-free cellular impedance. In contrast, alanine substitution of serines and threonines in the intracellular loop 3 of the H4R did not affect β-arrestin2 recruitment and receptor desensitization, but reduced β-arrestin1 recruitment and internalization. Hence, β-arrestin recruitment to H4R requires the putative phosphorylated serine cluster in the H4R C-terminal tail, whereas putative phosphosites in the intracellular loop 3 have different effects on β-arrestin1 versus β-arrestin2. Mutation of these putative phosphosites in either intracellular loop 3 or the C-terminal tail did not affect the histamine-induced recruitment of GRK2 and GRK3 but does change the interaction of H4R with GRK5 and GRK6, respectively. Identification of H4R interactions with these proteins is a first step in the understanding how this receptor might be dysregulated in pathophysiological conditions.
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Affiliation(s)
- Eléonore W E Verweij
- Division of Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Betty Al Araaj
- Division of Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Wimzy R Prabhata
- Division of Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Rudi Prihandoko
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Saskia Nijmeijer
- Division of Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Andrew B Tobin
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Rob Leurs
- Division of Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Henry F Vischer
- Division of Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
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5
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Hutchinson JL, Zhao X, Hill R, Mundell SJ. Arrestin-3 differentially regulates platelet GPCR subsets. Platelets 2019; 31:641-645. [PMID: 31684789 DOI: 10.1080/09537104.2019.1686754] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The principal demonstrated role of the nonvisual arrestins in vivo is to limit G protein-coupled receptor (GPCR) signaling. Nonetheless, a direct demonstration of this fundamental ability in platelets remains lacking, despite the prominent role played by GPCRs in platelet activation. This paper describes the basic characterization of the activatory responses of platelets from mice lacking arrestin-3 (arr3-/-), revealing pleiotropic roles dependent on GPCR ligand. Functionally, arrestin-3 acts as a brake on platelet aggregation regardless of ligand tested. Downstream of P2Y receptors, arr3-/- mice show increased secretion and integrin activation mirrored by enhanced intracellular calcium signaling and global PKC-dependent phosphorylation. Furthermore, P2Y12 receptor (P2Y12R) activity as assessed by ADP-mediated reduction of VASP phosphorylation is enhanced in arr3-/-mice. Downstream of PAR receptors there are similar increases in secretion and integrin activation in arr3-/- mice, together with enhanced PKC activity. Last, in arr3-/- mice the TP receptor displays unaltered PKC activity but markedly reduced calcium responses, which together with the kinetics of the aggregation response suggested a unique positive regulatory role for arrestin-3 in TP signaling. Overall, this paper reveals pleiotropic roles for arrestin-3 dependent on GPCR ligand describing for the first time a negative regulatory function for arrestin-3 in platelets.
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Affiliation(s)
- James L Hutchinson
- School of Physiology, Pharmacology and Neuroscience, University of Bristol , Bristol, UK, BS8 1TD
| | - Xiaojuan Zhao
- School of Physiology, Pharmacology and Neuroscience, University of Bristol , Bristol, UK, BS8 1TD
| | - Rob Hill
- School of Physiology, Pharmacology and Neuroscience, University of Bristol , Bristol, UK, BS8 1TD
| | - Stuart J Mundell
- School of Physiology, Pharmacology and Neuroscience, University of Bristol , Bristol, UK, BS8 1TD
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6
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von Kügelgen I. Pharmacology of P2Y receptors. Brain Res Bull 2019; 151:12-24. [PMID: 30922852 DOI: 10.1016/j.brainresbull.2019.03.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 03/04/2019] [Accepted: 03/17/2019] [Indexed: 01/17/2023]
Abstract
P2Y receptors are G-protein-coupled receptors (GPCRs) for extracellular nucleotides. There are eight mammalian P2Y receptor subtypes divided into two subgroups (P2Y1, P2Y2, P2Y4, P2Y6, and P2Y11) and (P2Y12, P2Y13, and P2Y14). The P2Y receptors are expressed in various cell types and play important roles in physiology and pathophysiology including inflammatory responses and neuropathic pain. The antagonism of P2Y12 receptors is used in pharmacotherapy for the prevention and therapy of cardiovascular events. The nucleoside analogue ticagrelor and active metabolites of the thienopyridine compounds ticlopidine, clopidogrel and prasugrel inhibit platelet P2Y12 receptors and reduce thereby platelet aggregation. The P2Y2 receptor agonist diquafosol is used for the treatment of the dry eye syndrome. The P2Y receptor subtypes differ in their amino acid sequences, their pharmacological profiles and their signaling transduction pathways. Recently, selective receptor ligands have been developed for all subtypes. The published crystal structures of the human P2Y1 and P2Y12 receptors as well as receptor models will facilitate the development of novel drugs for pharmacotherapy.
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Affiliation(s)
- Ivar von Kügelgen
- Department of Pharmacology and Toxicology, Pharma Center, University of Bonn, D-53127, Bonn, Germany.
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7
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8
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Gao ZG, Jacobson KA. Distinct Signaling Patterns of Allosteric Antagonism at the P2Y 1 Receptor. Mol Pharmacol 2017; 92:613-626. [PMID: 28864555 DOI: 10.1124/mol.117.109660] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 08/30/2017] [Indexed: 12/18/2022] Open
Abstract
Traditionally, G protein-coupled receptor antagonists are classified as competitive or noncompetitive and surmountable or insurmountable based on functional antagonism. P2Y1 receptor (P2Y1R) structures showed two antagonists binding to two spatially distinct sites: nucleotide MRS2500 (orthosteric, contacting the helical bundle) and urea BPTU (allosteric, on the external receptor surface). However, the nature of their P2Y1R antagonism has not been characterized. Here we characterized BPTU antagonism at various signaling pathways activated by structurally diverse agonists. BPTU rightward shifted the concentration-response curves of both 2-methylthioadenosine 5'-diphosphate trisodium salt and MRS2365 (5'-diphosphates) in some signaling events, such as extracellular signal-regulated kinase 1/2 and label free, in a parallel manner without affecting the maximum agonist effect (Emax) but antagonized insurmountably (suppressed agonist Emax) in signaling events such as guanosine 5'-3-O-(thio)triphosphate binding and β-arrestin2 recruitment. However, with dinucleotide Ap4A as an agonist, BPTU suppressed the Emax insurmountably in all signaling pathways. By comparison, MRS2500 behaved as surmountable antagonist rightward-shifting concentration-response curves of all three agonists in a parallel manner for all signaling pathways measured. Thus, we demonstrated a previously undocumented phenomenon that P2Y1R antagonism patterns could vary in different signaling pathways, which could be related to conformational selection, signaling amplification, and probe dependence. This phenomenon may apply generally to other receptors considering that antagonism by a specific ligand is often not compared at multiple signaling pathways. Thus, antagonism can be surmountable or insurmountable depending on the signaling pathways measured and the agonists used, which should be of broad relevance to drug discovery and disease treatment.
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Affiliation(s)
- Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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9
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Le Duc D, Schulz A, Lede V, Schulze A, Thor D, Brüser A, Schöneberg T. P2Y Receptors in Immune Response and Inflammation. Adv Immunol 2017; 136:85-121. [PMID: 28950952 DOI: 10.1016/bs.ai.2017.05.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Metabotropic pyrimidine and purine nucleotide receptors (P2Y receptors) are expressed in virtually all cells with implications in very diverse biological functions, including the well-established platelet aggregation (P2Y12), but also immune regulation and inflammation. The classical P2Y receptors bind nucleotides and are encoded by eight genes with limited sequence homology, while phylogenetically related receptors (e.g., P2Y12-like) recognize lipids and peptides, but also nucleotide derivatives. Growing lines of evidence suggest an important function of P2Y receptors in immune cell differentiation and maturation, migration, and cell apoptosis. Here, we give a perspective on the P2Y receptors' molecular structure and physiological importance in immune cells, as well as the related diseases and P2Y-targeting therapies. Extensive research is being undertaken to find modulators of P2Y receptors and uncover their physiological roles. We anticipate the medical applications of P2Y modulators and their immune relevance.
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Affiliation(s)
- Diana Le Duc
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Angela Schulz
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Vera Lede
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Annelie Schulze
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Doreen Thor
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Antje Brüser
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
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Dores MR, Grimsey NJ, Mendez F, Trejo J. ALIX Regulates the Ubiquitin-Independent Lysosomal Sorting of the P2Y1 Purinergic Receptor via a YPX3L Motif. PLoS One 2016; 11:e0157587. [PMID: 27301021 PMCID: PMC4907476 DOI: 10.1371/journal.pone.0157587] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/01/2016] [Indexed: 12/22/2022] Open
Abstract
Endocytic sorting and lysosomal degradation are integral to the regulation of G protein-coupled receptor (GPCR) function. Upon ligand binding, classical GPCRs are activated, internalized and recycled or sorted to lysosomes for degradation, a process that requires receptor ubiquitination. However, recent studies have demonstrated that numerous GPCRs are sorted to lysosomes independent of receptor ubiquitination. Here, we describe an ubiquitin-independent lysosomal sorting pathway for the purinergic GPCR P2Y1. After activation, P2Y1 sorts to lysosomes for degradation independent of direct ubiquitination that is mediated by a YPX3L motif within the second intracellular loop that serves as a binding site for the adaptor protein ALIX. Depletion of ALIX or site-directed mutation of the YPX3L motif inhibits P2Y1 sorting into the lumen of multivesicular endosomes/lysosomes and degradation. These findings confirm the function of YPX3L motifs as lysosomal targeting sequences for GPCRs and demonstrate that ALIX mediates the ubiquitin-independent degradation of certain GPCRs.
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Affiliation(s)
- Michael R. Dores
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA 92093, United States of America
- Department of Biology, Hofstra University, Hempstead, NY 11549, United States of America
| | - Neil J. Grimsey
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA 92093, United States of America
| | - Francisco Mendez
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA 92093, United States of America
| | - JoAnn Trejo
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA 92093, United States of America
- * E-mail:
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11
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Intracellular expression of purinoceptors. Purinergic Signal 2015; 11:275-6. [PMID: 26009501 DOI: 10.1007/s11302-015-9455-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 05/15/2015] [Indexed: 10/23/2022] Open
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12
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Dynamics of inhibitory co-transmission, membrane potential and pacemaker activity determine neuromyogenic function in the rat colon. Pflugers Arch 2014; 466:2305-21. [DOI: 10.1007/s00424-014-1500-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 02/26/2014] [Accepted: 03/10/2014] [Indexed: 01/26/2023]
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13
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Abstract
G-protein-coupled receptors (GPCRs) are the primary interaction partners for arrestins. The visual arrestins, arrestin1 and arrestin4, physiologically bind to only very few receptors, i.e., rhodopsin and the color opsins, respectively. In contrast, the ubiquitously expressed nonvisual variants β-arrestin1 and 2 bind to a large number of receptors in a fairly nonspecific manner. This binding requires two triggers, agonist activation and receptor phosphorylation by a G-protein-coupled receptor kinase (GRK). These two triggers are mediated by two different regions of the arrestins, the "phosphorylation sensor" in the core of the protein and a less well-defined "activation sensor." Binding appears to occur mostly in a 1:1 stoichiometry, involving the N-terminal domain of GPCRs, but in addition a second GPCR may loosely bind to the C-terminal domain when active receptors are abundant.Arrestin binding initially uncouples GPCRs from their G-proteins. It stabilizes receptors in an active conformation and also induces a conformational change in the arrestins that involves a rotation of the two domains relative to each other plus changes in the polar core. This conformational change appears to permit the interaction with further downstream proteins. The latter interaction, demonstrated mostly for β-arrestins, triggers receptor internalization as well as a number of nonclassical signaling pathways.Open questions concern the exact stoichiometry of the interaction, possible specificity with regard to the type of agonist and of GRK involved, selective regulation of downstream signaling (=biased signaling), and the options to use these mechanisms as therapeutic targets.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Straße 9, 97078, Würzburg, Germany,
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Gärtner F, Seidel T, Schulz U, Gummert J, Milting H. Desensitization and internalization of endothelin receptor A: impact of G protein-coupled receptor kinase 2 (GRK2)-mediated phosphorylation. J Biol Chem 2013; 288:32138-32148. [PMID: 24064210 DOI: 10.1074/jbc.m113.461566] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endothelin receptor A (ETA), a G protein-coupled receptor, mediates endothelin signaling, which is regulated by GRK2. Three Ser and seven Thr residues recently proven to be phosphoacceptor sites are located in the C-terminal extremity (CTE) of the receptor following its palmitoylation site. We created various phosphorylation-deficient ETA mutants. The phospholipase C activity of mutant receptors in HEK-293 cells was analyzed during continuous endothelin stimulation to investigate the impact of phosphorylation sites on ETA desensitization. Total deletion of phosphoacceptor sites in the CTE affected proper receptor regulation. However, proximal and distal phosphoacceptor sites both turned out to be sufficient to induce WT-like desensitization. Overexpression of the Gαq coupling-deficient mutant GRK2-D110A suppressed ETA-WT signaling but failed to decrease phospholipase C activity mediated by the phosphorylation-deficient mutant ETA-6PD. In contrast, GRK2-WT acted on both receptors, whereas the kinase-inactive mutant GRK2-D110A/K220R failed to inhibit signaling of ETA-WT and ETA-6PD. This demonstrates that ETA desensitization involves at least two autonomous GRK2-mediated components: 1) a phosphorylation-independent signal decrease mediated by blocking of Gαq and 2) a mechanism involving phosphorylation of Ser and Thr residues in the CTE of the receptor in a redundant fashion, able to incorporate either proximal or distal phosphoacceptor sites. High level transfection of GRK2 variants influenced signaling of ETA-WT and ETA-6PD and hints at an additional phosphorylation-independent regulatory mechanism. Furthermore, internalization of mRuby-tagged receptors was observed with ETA-WT and the phosphorylation-deficient mutant ETA-14PD (lacking 14 phosphoacceptor sites) and turned out to be based on a phosphorylation-independent mechanism.
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Affiliation(s)
- Florian Gärtner
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen
| | - Thorsten Seidel
- Dynamic Cell Imaging, Faculty of Biology, Bielefeld University, D-33501 Bielefeld, Germany
| | - Uwe Schulz
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen
| | - Jan Gummert
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen
| | - Hendrik Milting
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen.
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15
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Zhao J, Pei G. Arrestins in metabolic regulation. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 118:413-27. [PMID: 23764063 DOI: 10.1016/b978-0-12-394440-5.00016-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This review summarizes the regulatory roles of β-arrestins in whole-body energy balance, body weight control, and carbohydrate and lipid homeostasis. Much research has pointed in the direction of the functions of β-arrestins in mediating desensitization and endocytosis of G protein-coupled receptors as well as in activating the receptor/β-arrestin/ERK signaling pathway being crucial for metabolic regulation. Furthermore, β-arrestins form diverse signal complexes for the activation of the downstream cassettes for the body's metabolic reactions. However, further studies are required to fully address the emerging roles of β-arrestins in metabolic regulation and related diseases.
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Affiliation(s)
- Jian Zhao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, PR China
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Walther C, Ferguson SSG. Arrestins: role in the desensitization, sequestration, and vesicular trafficking of G protein-coupled receptors. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 118:93-113. [PMID: 23764051 DOI: 10.1016/b978-0-12-394440-5.00004-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Over the years, β-arrestins have emerged as multifunctional molecular scaffolding proteins regulating almost every imaginable G protein-coupled receptor (GPCR) function. Originally discovered as GPCR-desensitizing molecules, they have been shown to also serve as important regulators of GPCR signaling, sequestration, and vesicular trafficking. This broad functional role implicates β-arrestins as key regulatory proteins for cellular function. Hence, this chapter summarizes the current understanding of the β-arrestin family's unique ability to control the kinetics as well as the extent of GPCR activity at the level of desensitization, sequestration, and subsequent intracellular trafficking.
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Affiliation(s)
- Cornelia Walther
- J. Allyn Taylor Centre for Cell Biology, Robarts Research Institute, Western University Canada, London, Ontario, Canada
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Gachet C. P2Y(12) receptors in platelets and other hematopoietic and non-hematopoietic cells. Purinergic Signal 2012; 8:609-19. [PMID: 22528678 DOI: 10.1007/s11302-012-9303-x] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 01/20/2012] [Indexed: 12/31/2022] Open
Abstract
The P2Y(12) receptor is a Gi-coupled ADP receptor first described in blood platelets where it plays a central role in the complex processes of activation and aggregation. Platelet granules store important amounts of ADP which are released upon stimulation by interaction of platelets with the damaged vessel wall. Therefore, the P2Y(12) receptor is a key player in primary hemostasis and in arterial thrombosis and is an established target of antithrombotic drugs like the thienopyridine compounds ticlopidine, clopidogrel, and prasugrel or the direct, reversible antagonists ticagrelor and cangrelor. Beyond the platelet physiology and pharmacology, recent studies have revealed the expression of the P2Y(12) receptor in other hematopoietic cells including leukocyte subtypes and microglia in the central nervous system as well as in vascular smooth muscle cells. These studies indicate putative roles of the P2Y(12) receptor in inflammatory states and diseases of the brain, lung, and blood vessels. The selective role of P2Y(12) among other P2 receptors as well as the possible impact of P2Y(12) targeting drugs in these processes remain to be evaluated.
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Affiliation(s)
- Christian Gachet
- UMR_S949 Inserm, Université de Strasbourg, EFS-Alsace 10, rue Spielmann, BP N°36, 67065, Strasbourg, France.
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Lohse MJ, Nuber S, Hoffmann C. Fluorescence/bioluminescence resonance energy transfer techniques to study G-protein-coupled receptor activation and signaling. Pharmacol Rev 2012; 64:299-336. [PMID: 22407612 DOI: 10.1124/pr.110.004309] [Citation(s) in RCA: 251] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Fluorescence and bioluminescence resonance energy transfer (FRET and BRET) techniques allow the sensitive monitoring of distances between two labels at the nanometer scale. Depending on the placement of the labels, this permits the analysis of conformational changes within a single protein (for example of a receptor) or the monitoring of protein-protein interactions (for example, between receptors and G-protein subunits). Over the past decade, numerous such techniques have been developed to monitor the activation and signaling of G-protein-coupled receptors (GPCRs) in both the purified, reconstituted state and in intact cells. These techniques span the entire spectrum from ligand binding to the receptors down to intracellular second messengers. They allow the determination and the visualization of signaling processes with high temporal and spatial resolution. With these techniques, it has been demonstrated that GPCR signals may show spatial and temporal patterning. In particular, evidence has been provided for spatial compartmentalization of GPCRs and their signals in intact cells and for distinct physiological consequences of such spatial patterning. We review here the FRET and BRET technologies that have been developed for G-protein-coupled receptors and their signaling proteins (G-proteins, effectors) and the concepts that result from such experiments.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, Versbacher Str. 9, 97078 Würzburg, Germany.
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Schaff M, Receveur N, Bourdon C, Ohlmann P, Lanza F, Gachet C, Mangin PH. β-arrestin-1 participates in thrombosis and regulates integrin aIIbβ3 signalling without affecting P2Y receptors desensitisation and function. Thromb Haemost 2012; 107:735-48. [PMID: 22318609 DOI: 10.1160/th11-06-0430] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 01/05/2012] [Indexed: 01/21/2023]
Abstract
β-arrestin-1 (β-arr1) and β-arrestin-2 (β-arr2) are cytosolic proteins well-known to participate in G protein-coupled receptor desensitisation and signalling. We used genetically-inactivated mice to evaluate the role of β-arr1 or β-arr2 in platelet function, P2Y receptor desensitisation, haemostasis and thrombosis. Platelet aggregation, soluble fibrinogen binding and P-selectin exposure induced by various agonists were near normal in β-arr1-/- and β-arr2-/- platelets. In addition, deficiency in β-arr1 or β-arr2 was not critical for P2Y receptors desensitisation. A functional redundancy between β-arr1 and β-arr2 may explain these unchanged platelet responses. Interestingly, β-arr1-/- but not β-arr2-/- mice were protected against laser- and FeCl3-induced thrombosis. The tail bleeding times, number of rebleeds and volume of blood loss were unchanged in β-arr1-/- and β-arr2-/- mice, suggesting no defect in haemostasis. β-arr1-/- platelet activation upon adhesion to immobilised fibrinogen was inhibited, as attested by a 37 ± 5% (n = 3, p<0.0001) decrease in filopodia extension, suggesting defective signalling through integrin αIIbβ3. β-arr1 appeared to be located downstream of Src family kinases and to regulate αIIbβ3 signalling by increasing Akt phosphorylation. Overall, this study supports a role for β-arr1 in promoting thrombus formation, in part through its participation in αIIbβ3 signalling, and no role of β-arr1 and β-arr2 in agonist-induced platelet activation and P2Y receptors desensitisation.
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Affiliation(s)
- M Schaff
- INSERM UMR-S949, Etablissement Français du Sang-Alsace (EFS-Alsace), 10, rue Spielmann, BP 36, F-67065 Strasbourg Cedex, France
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20
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P2 receptors and platelet function. Purinergic Signal 2011; 7:293-303. [PMID: 21792575 DOI: 10.1007/s11302-011-9247-6] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/10/2011] [Indexed: 01/11/2023] Open
Abstract
Following vessel wall injury, platelets adhere to the exposed subendothelium, become activated and release mediators such as TXA(2) and nucleotides stored at very high concentration in the so-called dense granules. Released nucleotides and other soluble agents act in a positive feedback mechanism to cause further platelet activation and amplify platelet responses induced by agents such as thrombin or collagen. Adenine nucleotides act on platelets through three distinct P2 receptors: two are G protein-coupled ADP receptors, namely the P2Y(1) and P2Y(12) receptor subtypes, while the P2X(1) receptor ligand-gated cation channel is activated by ATP. The P2Y(1) receptor initiates platelet aggregation but is not sufficient for a full platelet aggregation in response to ADP, while the P2Y(12) receptor is responsible for completion of the aggregation to ADP. The latter receptor, the molecular target of the antithrombotic drugs clopidogrel, prasugrel and ticagrelor, is responsible for most of the potentiating effects of ADP when platelets are stimulated by agents such as thrombin, collagen or immune complexes. The P2X(1) receptor is involved in platelet shape change and in activation by collagen under shear conditions. Each of these receptors is coupled to specific signal transduction pathways in response to ADP or ATP and is differentially involved in all the sequential events involved in platelet function and haemostasis. As such, they represent potential targets for antithrombotic drugs.
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Qi AD, Houston-Cohen D, Naruszewicz I, Harden TK, Nicholas RA. Ser352 and Ser354 in the carboxyl terminus of the human P2Y(1) receptor are required for agonist-promoted phosphorylation and internalization in MDCK cells. Br J Pharmacol 2011; 162:1304-13. [PMID: 21108629 PMCID: PMC3058163 DOI: 10.1111/j.1476-5381.2010.01135.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 09/23/2010] [Accepted: 10/26/2010] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE The P2Y(1) receptor promotes chloride secretion in epithelial cells, a process critical for regulation of extracellular ion and fluid levels. Here we have examined the role of phosphorylation in agonist-induced internalization of P2Y(1) receptors. EXPERIMENTAL APPROACH A high-affinity radiolabelled antagonist, MRS2500, was used to quantify cell surface-binding sites of P2Y(1) receptors in Madin-Darby canine kidney (MDCK) epithelial cells, following exposure to agonists. The regions in the carboxyl terminus involved in both agonist-induced internalization of the receptor and its phosphorylation were identified by mutational analysis. KEY RESULTS Endogenous and stably expressed recombinant P2Y(1) receptors rapidly internalized with similar time courses in response to agonist in MDCK cells, ensuring that the levels of recombinant receptor achieved by retroviral infection did not adversely affect function of the internalization machinery. Four protein kinase C inhibitors of varying specificity did not affect internalization of recombinant receptors. Agonist-promoted internalization of a series of truncated P2Y(1) receptors identified a region between residues 349 and 359 in the carboxyl terminus as critical for regulation. Two amino acids within this region, Ser352 and Ser354, were shown to be both necessary and sufficient for agonist-promoted receptor phosphorylation and internalization. CONCLUSIONS AND IMPLICATIONS Our results firmly establish Ser352 and Ser354 in the carboxyl terminus of P2Y(1) receptors as critical residues for agonist-induced receptor internalization in MDCK cells. As the mechanism mediating this regulation requires phosphorylation of these key residues, the relevant receptor-regulated protein kinase can now be identified.
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Affiliation(s)
- Ai-Dong Qi
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA
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Molecular pharmacology, physiology, and structure of the P2Y receptors. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2011; 61:373-415. [PMID: 21586365 DOI: 10.1016/b978-0-12-385526-8.00012-6] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The P2Y receptors are a widely expressed group of eight nucleotide-activated G protein-coupled receptors (GPCRs). The P2Y(1)(ADP), P2Y(2)(ATP/UTP), P2Y(4)(UTP), P2Y(6)(UDP), and P2Y(11)(ATP) receptors activate G(q) and therefore robustly promote inositol lipid signaling responses. The P2Y(12)(ADP), P2Y(13)(ADP), and P2Y(14)(UDP/UDP-glucose) receptors activate G(i) leading to inhibition of adenylyl cyclase and to Gβγ-mediated activation of a range of effector proteins including phosphoinositide 3-kinase-γ, inward rectifying K(+) (GIRK) channels, phospholipase C-β2 and -β3, and G protein-receptor kinases 2 and 3. A broad range of physiological responses occur downstream of activation of these receptors ranging from Cl(-) secretion by epithelia to aggregation of platelets to neurotransmission. Useful structural models of the P2Y receptors have evolved from extensive genetic analyses coupled with molecular modeling based on three-dimensional structures obtained for rhodopsin and several other GPCRs. Selective ligands have been synthesized for most of the P2Y receptors with the most prominent successes attained with highly selective agonist and antagonist molecules for the ADP-activated P2Y(1) and P2Y(12) receptors. The widely prescribed drug, clopidogrel, which results in irreversible blockade of the platelet P2Y(12) receptor, is the most important therapeutic agent that targets a P2Y receptor.
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Walther C, Nagel S, Gimenez LE, Mörl K, Gurevich VV, Beck-Sickinger AG. Ligand-induced internalization and recycling of the human neuropeptide Y2 receptor is regulated by its carboxyl-terminal tail. J Biol Chem 2010; 285:41578-90. [PMID: 20959467 DOI: 10.1074/jbc.m110.162156] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Agonist-induced internalization of G protein-coupled receptors plays an important role in signal regulation. The underlying mechanisms of the internalization of the human neuropeptide Y(2) receptor (hY(2)R), as well as its desensitization, endocytosis, and resensitization are mainly unknown. In the present study we have investigated the role of carboxyl-terminal (C-terminal) Ser/Thr residues and acidic amino acids in regulating receptor internalization, arrestin interaction, and recycling by fluorescence microscopy, cell surface enzyme-linked immunosorbent assay, and bioluminescence resonance energy transfer in several cell lines. Strikingly, C-terminal truncation mutants revealed two different internalization motifs. Whereas a distal motif (373)DSXTEXT(379) was found to be the primary regulatory internalization sequence acting in concert with arrestin-3, the proximal motif (347)DXXXSEXSXT(356) promoted ligand-induced internalization in an arrestin-3-independent manner. Moreover, we identified a regulatory sequence located between these internalization motifs ((357)FKAKKNLEVRKN(368)), which serves as an inhibitory element. We found that hY(2)R recycling is also governed by structural determinants within the proximal internalization motif. In conclusion, these results indicate that the hY(2)R C terminus is involved in multiple molecular events that regulate internalization, interaction with arrestin-3, and receptor resensitization. Our findings provide novel insights into complex mechanisms of controlled internalization of hY(2)R, which is likely applicable to other GPCRs.
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Affiliation(s)
- Cornelia Walther
- Faculty of Biosciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103 Leipzig, Germany
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Reiner S, Ambrosio M, Hoffmann C, Lohse MJ. Differential signaling of the endogenous agonists at the beta2-adrenergic receptor. J Biol Chem 2010; 285:36188-98. [PMID: 20837485 DOI: 10.1074/jbc.m110.175604] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The concept of "functional selectivity" or "biased signaling" suggests that a ligand can have distinct efficacies with regard to different signaling pathways. We have investigated the question of whether biased signaling may be related to distinct agonist-induced conformational changes in receptors using the β(2)-adrenergic receptor (β(2)AR) and its two endogenous ligands epinephrine and norepinephrine as a model system. Agonist-induced conformational changes were determined in a fluorescently tagged β(2)AR FRET sensor. In this β(2)AR sensor, norepinephrine caused signals that amounted to only ≈50% of those induced by epinephrine and the standard "full" agonist isoproterenol. Furthermore, norepinephrine-induced changes in the β(2)AR FRET sensor were slower than those induced by epinephrine (rate constants, 47 versus 128 ms). A similar partial β(2)AR activation signal was revealed for the synthetic agonists fenoterol and terbutaline. However, norepinephrine was almost as efficient as epinephrine (and isoproterenol) in causing activation of G(s) and adenylyl cyclase. In contrast, fenoterol was quite efficient in triggering β-arrestin2 recruitment to the cell surface and its interaction with β(2)AR, as well as internalization of the receptors, whereas norepinephrine caused partial and slow changes in these assays. We conclude that partial agonism of norepinephrine at the β(2)AR is related to the induction of a different active conformation and that this conformation is efficient in signaling to G(s) and less efficient in signaling to β-arrestin2. These observations extend the concept of biased signaling to the endogenous agonists of the β(2)AR and link it to distinct conformational changes in the receptor.
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Affiliation(s)
- Susanne Reiner
- Institute of Pharmacology and Toxicology, Versbacher Strasse 9, D-97078 Würzburg, Germany
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