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Integration and Spatial Organization of Signaling by G Protein-Coupled Receptor Homo- and Heterodimers. Biomolecules 2021; 11:biom11121828. [PMID: 34944469 PMCID: PMC8698773 DOI: 10.3390/biom11121828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 11/29/2021] [Accepted: 12/01/2021] [Indexed: 01/14/2023] Open
Abstract
Information flow from a source to a receiver becomes informative when the recipient can process the signal into a meaningful form. Information exchange and interpretation is essential in biology and understanding how cells integrate signals from a variety of information-coding molecules into complex orchestrated responses is a major challenge for modern cell biology. In complex organisms, cell to cell communication occurs mostly through neurotransmitters and hormones, and receptors are responsible for signal recognition at the membrane level and information transduction inside the cell. The G protein-coupled receptors (GPCRs) are the largest family of membrane receptors, with nearly 800 genes coding for these proteins. The recognition that GPCRs may physically interact with each other has led to the hypothesis that their dimeric state can provide the framework for temporal coincidence in signaling pathways. Furthermore, the formation of GPCRs higher order oligomers provides the structural basis for organizing distinct cell compartments along the plasma membrane where confined increases in second messengers may be perceived and discriminated. Here, we summarize evidence that supports these conjectures, fostering new ideas about the physiological role played by receptor homo- and hetero-oligomerization in cell biology.
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2
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Palmer CB, Meyrath M, Canals M, Kostenis E, Chevigné A, Szpakowska M. Atypical opioid receptors: unconventional biology and therapeutic opportunities. Pharmacol Ther 2021; 233:108014. [PMID: 34624426 DOI: 10.1016/j.pharmthera.2021.108014] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 09/13/2021] [Accepted: 09/27/2021] [Indexed: 12/13/2022]
Abstract
Endogenous opioid peptides and prescription opioid drugs modulate pain, anxiety and stress by activating four opioid receptors, namely μ (mu, MOP), δ (delta, DOP), κ (kappa, KOP) and the nociceptin/orphanin FQ receptor (NOP). Interestingly, several other receptors are also activated by endogenous opioid peptides and influence opioid-driven signaling and biology. However, they do not meet the criteria to be recognized as classical opioid receptors, as they are phylogenetically distant from them and are insensitive to classical non-selective opioid receptor antagonists (e.g. naloxone). Nevertheless, accumulating reports suggest that these receptors may be interesting alternative targets, especially for the development of safer analgesics. Five of these opioid peptide-binding receptors belong to the family of G protein-coupled receptors (GPCRs)-two are members of the Mas-related G protein-coupled receptor X family (MrgX1, MrgX2), two of the bradykinin receptor family (B1, B2), and one is an atypical chemokine receptor (ACKR3). Additionally, the ion channel N-methyl-d-aspartate receptors (NMDARs) are also activated by opioid peptides. In this review, we recapitulate the implication of these alternative receptors in opioid-related disorders and discuss their unconventional biology, with members displaying signaling to scavenging properties. We provide an overview of their established and emerging roles and pharmacology in the context of pain management, as well as their clinical relevance as alternative targets to overcome the hurdles of chronic opioid use. Given the involvement of these receptors in a wide variety of functions, including inflammation, chemotaxis, anaphylaxis or synaptic transmission and plasticity, we also discuss the challenges associated with the modulation of both their canonical and opioid-driven signaling.
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Affiliation(s)
- Christie B Palmer
- Immuno-Pharmacology and Interactomics, Department of Infection and Immunity, Luxembourg Institute of Health (LIH), Esch-sur-Alzette, Luxembourg; Faculty of Science, Technology and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Max Meyrath
- Immuno-Pharmacology and Interactomics, Department of Infection and Immunity, Luxembourg Institute of Health (LIH), Esch-sur-Alzette, Luxembourg
| | - Meritxell Canals
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK; Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, UK
| | - Evi Kostenis
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Andy Chevigné
- Immuno-Pharmacology and Interactomics, Department of Infection and Immunity, Luxembourg Institute of Health (LIH), Esch-sur-Alzette, Luxembourg.
| | - Martyna Szpakowska
- Immuno-Pharmacology and Interactomics, Department of Infection and Immunity, Luxembourg Institute of Health (LIH), Esch-sur-Alzette, Luxembourg
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3
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McMillan H, Lundy FT, Dunne OM, Al-Natour B, Jeanneau C, About I, Curtis TM, El Karim I. Endogenous Mas-related G-protein-coupled receptor X1 activates and sensitizes TRPA1 in a human model of peripheral nerves. FASEB J 2021; 35:e21492. [PMID: 33788969 DOI: 10.1096/fj.202001667rr] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 02/16/2021] [Accepted: 02/16/2021] [Indexed: 12/21/2022]
Abstract
Mas-related G-protein-coupled receptor X1 (MrgprX1) is a human-specific Mrgpr and its expression is restricted to primary sensory neurons. However, its role in nociception and pain signaling pathways is largely unknown. This study aims to investigate a role for MrgprX1 in nociception via interaction with the pain receptor, Transient Receptor Potential Ankyrin 1 (TRPA1), using in-vitro and in-vivo human neuronal models. MrgprX1 protein expression in human trigeminal nociceptors was investigated by the immunolabeling of the dental pulp and cultured peripheral neuronal equivalent (PNE) cells. MrgprX1 receptor signaling was monitored by Fura-2-based Ca2+ imaging using PNEs and membrane potential responses were measured using FluoVoltTM . Immunofluorescent staining revealed MrgprX1 expression in-vivo in dental afferents, which was more intense in inflamed compared to healthy dental pulps. Endogenous MrgprX1 protein expression was confirmed in the in-vitro human PNE model. MrgprX1 receptor signaling and the mechanisms through which it couples to TRPA1 were studied by Ca2+ imaging. Results showed that MrgprX1 activates TRPA1 and induces membrane depolarization in a TRPA1 dependent manner. In addition, MrgprX1 sensitizes TRPA1 to agonist stimulation via Protein Kinase C (PKC). The activation and sensitization of TRPA1 by MrgprX1 in a model of human nerves suggests an important role for this receptor in the modulation of nociception.
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Affiliation(s)
- Hayley McMillan
- School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, UK
| | - Fionnuala T Lundy
- School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, UK
| | - Orla M Dunne
- School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, UK
| | - Banan Al-Natour
- School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, UK
- Department of Oral Medicine and Oral Surgery, Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan
| | | | - Imad About
- Aix Marseille Univ, CNRS, ISM, Inst Movement Sci, Marseille, France
| | - Tim M Curtis
- School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, UK
| | - Ikhlas El Karim
- School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, UK
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4
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Abid MSR, Mousavi S, Checco JW. Identifying Receptors for Neuropeptides and Peptide Hormones: Challenges and Recent Progress. ACS Chem Biol 2021; 16:251-263. [PMID: 33539706 DOI: 10.1021/acschembio.0c00950] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Intercellular signaling events mediated by neuropeptides and peptide hormones represent important targets for both basic science and drug discovery. For many bioactive peptides, the protein receptors that transmit information across the receiving cell membrane are not known, severely limiting these signaling pathways as potential therapeutic targets. Identifying the receptor(s) for a given peptide of interest is complicated by several factors. Most notably, cell-cell signaling peptides are generated through dynamic biosynthetic pathways, can act on many different families of receptor proteins, and can participate in complex ligand-receptor interactions that extend beyond a simple one-to-one archetype. Here, we discuss recent methodological advances to identify signaling partners for bioactive peptides. Recent efforts have centered on methods to identify candidate receptors via transcript expression, methods to match peptide-receptor pairs through high throughput screening, and methods to capture direct ligand-receptor interactions using chemical probes. Future applications of the receptor identification approaches discussed here, as well as technical advancements to address their limitations, promise to lead to a greater understanding of how cells communicate to deliver complex physiologies. Importantly, such advancements will likely provide novel targets for the treatment of human diseases within the central nervous and endocrine systems.
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Affiliation(s)
- Md Shadman Ridwan Abid
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Somayeh Mousavi
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - James W. Checco
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
- The Nebraska Center for Integrated Biomolecular Communication (NCIBC), University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
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5
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Abstract
Opioids, such as morphine and fentanyl, are widely used for the treatment of severe pain; however, prolonged treatment with these drugs leads to the development of tolerance and can lead to opioid use disorder. The "Opioid Epidemic" has generated a drive for a deeper understanding of the fundamental signaling mechanisms of opioid receptors. It is generally thought that the three types of opioid receptors (μ, δ, κ) are activated by endogenous peptides derived from three different precursors: Proopiomelanocortin, proenkephalin, and prodynorphin. Posttranslational processing of these precursors generates >20 peptides with opioid receptor activity, leading to a long-standing question of the significance of this repertoire of peptides. Here, we address some aspects of this question using a technical tour de force approach to systematically evaluate ligand binding and signaling properties ([35S]GTPγS binding and β-arrestin recruitment) of 22 peptides at each of the three opioid receptors. We show that nearly all tested peptides are able to activate the three opioid receptors, and many of them exhibit agonist-directed receptor signaling (functional selectivity). Our data also challenge the dogma that shorter forms of β-endorphin do not exhibit receptor activity; we show that they exhibit robust signaling in cultured cells and in an acute brain slice preparation. Collectively, this information lays the groundwork for improved understanding of the endogenous opioid system that will help in developing more effective treatments for pain and addiction.
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Gendron L, Cahill CM, von Zastrow M, Schiller PW, Pineyro G. Molecular Pharmacology of δ-Opioid Receptors. Pharmacol Rev 2017; 68:631-700. [PMID: 27343248 DOI: 10.1124/pr.114.008979] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Opioids are among the most effective analgesics available and are the first choice in the treatment of acute severe pain. However, partial efficacy, a tendency to produce tolerance, and a host of ill-tolerated side effects make clinically available opioids less effective in the management of chronic pain syndromes. Given that most therapeutic opioids produce their actions via µ-opioid receptors (MOPrs), other targets are constantly being explored, among which δ-opioid receptors (DOPrs) are being increasingly considered as promising alternatives. This review addresses DOPrs from the perspective of cellular and molecular determinants of their pharmacological diversity. Thus, DOPr ligands are examined in terms of structural and functional variety, DOPrs' capacity to engage a multiplicity of canonical and noncanonical G protein-dependent responses is surveyed, and evidence supporting ligand-specific signaling and regulation is analyzed. Pharmacological DOPr subtypes are examined in light of the ability of DOPr to organize into multimeric arrays and to adopt multiple active conformations as well as differences in ligand kinetics. Current knowledge on DOPr targeting to the membrane is examined as a means of understanding how these receptors are especially active in chronic pain management. Insight into cellular and molecular mechanisms of pharmacological diversity should guide the rational design of more effective, longer-lasting, and better-tolerated opioid analgesics for chronic pain management.
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Affiliation(s)
- Louis Gendron
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Catherine M Cahill
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Mark von Zastrow
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Peter W Schiller
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Graciela Pineyro
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
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Brackley AD, Sarrami S, Gomez R, Guerrero KA, Jeske NA. Identification of a signaling cascade that maintains constitutive δ-opioid receptor incompetence in peripheral sensory neurons. J Biol Chem 2017; 292:8762-8772. [PMID: 28381559 DOI: 10.1074/jbc.m117.776799] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/29/2017] [Indexed: 12/17/2022] Open
Abstract
μ-Opioid receptor (MOR) agonists are often used to treat severe pain but can result in adverse side effects. To circumvent systemic side effects, targeting peripheral opioid receptors is an attractive alternative treatment for severe pain. Activation of the δ-opioid receptor (DOR) produces similar analgesia with reduced side effects. However, until primed by inflammation, peripheral DOR is analgesically incompetent, raising interest in the mechanism. We recently identified a novel role for G-protein-coupled receptor kinase 2 (GRK2) that renders DOR analgesically incompetent at the plasma membrane. However, the mechanism that maintains constitutive GRK2 association with DOR is unknown. Protein kinase A (PKA) phosphorylation of GRK2 at Ser-685 targets it to the plasma membrane. Protein kinase A-anchoring protein 79/150 (AKAP), residing at the plasma membrane in neurons, scaffolds PKA to target proteins to mediate downstream signal. Therefore, we sought to determine whether GRK2-mediated DOR desensitization is directed by PKA via AKAP scaffolding. Membrane fractions from cultured rat sensory neurons following AKAP siRNA transfection and from AKAP-knock-out mice had less PKA activity, GRK2 Ser-685 phosphorylation, and GRK2 plasma membrane targeting than controls. Site-directed mutagenesis revealed that GRK2 Ser-685 phosphorylation drives the association of GRK2 with plasma membrane-associated DOR. Moreover, overexpression studies with AKAP mutants indicated that impaired AKAP-mediated PKA scaffolding significantly reduces DOR-GRK2 association at the plasma membrane and consequently increases DOR activity in sensory neurons without a priming event. These findings suggest that AKAP scaffolds PKA to increase plasma membrane targeting and phosphorylation of GRK2 to maintain DOR analgesic incompetence in peripheral sensory neurons.
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Affiliation(s)
| | | | | | | | - Nathaniel A Jeske
- From the Departments of Pharmacology, .,Oral and Maxillofacial Surgery, and.,Physiology, University of Texas Health Science Center, San Antonio, Texas 78229
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8
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Blockade of neuronal dopamine D2 receptor attenuates morphine tolerance in mice spinal cord. Sci Rep 2016; 6:38746. [PMID: 28004735 PMCID: PMC5177930 DOI: 10.1038/srep38746] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 11/14/2016] [Indexed: 12/23/2022] Open
Abstract
Tolerance induced by morphine remains a major unresolved problem and significantly limits its clinical use. Recent evidences have indicated that dopamine D2 receptor (D2DR) is likely to be involved in morphine-induced antinociceptive tolerance. However, its exact effect and molecular mechanism remain unknown. In this study we examined the effect of D2DR on morphine antinociceptive tolerance in mice spinal cord. Chronic morphine treatment significantly increased levels of D2DR in mice spinal dorsal horn. And the immunoreactivity of D2DR was newly expressed in neurons rather than astrocytes or microglia both in vivo and in vitro. Blockade of D2DR with its antagonist (sulpiride and L-741,626, i.t.) attenuated morphine antinociceptive tolerance without affecting basal pain perception. Sulpiride (i.t.) also down-regulated the expression of phosphorylation of NR1, PKC, MAPKs and suppressed the activation of astrocytes and microglia induced by chronic morphine administration. Particularly, D2DR was found to interact with μ opioid receptor (MOR) in neurons, and chronic morphine treatment enhanced the MOR/D2DR interactions. Sulpiride (i.t.) could disrupt the MOR/D2DR interactions and attenuate morphine tolerance, indicating that neuronal D2DR in the spinal cord may be involved in morphine tolerance possibly by interacting with MOR. These results may present new opportunities for the treatment and management of morphine-induced antinociceptive tolerance which often observed in clinic.
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Łukasiewicz S, Błasiak E, Szafran-Pilch K, Dziedzicka-Wasylewska M. Dopamine D2 and serotonin 5-HT1A receptor interaction in the context of the effects of antipsychotics - in vitro studies. J Neurochem 2016; 137:549-60. [PMID: 26876117 DOI: 10.1111/jnc.13582] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 12/11/2022]
Abstract
The serotonin 5-HT1A receptor (5-HT1 A R) and dopamine D2 receptor (D2 R) have been implicated as important sites of action in antipsychotics. Several lines of evidence indicate the key role of G protein-coupled receptors (GPCRs) heteromers in pathophysiology of schizophrenia and highlight these complexes as novel drug targets. Because heterodimers can form only on those cells co-expressing constituent receptors, they present a target of high pharmacological specificity in the context of biochemical effects induced by antipsychotic drugs. In studies conducted in the HEK 293 cell line, we demonstrated that 5-HT1 A R and D2 R are able to form constitutive heterodimers, and antipsychotic drugs (clozapine, olanzapine, aripiprazole, and lurasidone) enhanced this process, with clozapine being most effective. Various functional tests (cAMP and IP1 as well as ERK activation) indicated that the drugs had different effects on signal transduction by the heteromer. Interestingly, co-incubation of heterodimer-expressing HEK 293 cells with clozapine and the 5-HT1 A R agonist 8-OH DPAT potentiated post-synaptic effects, especially with respect to ERK activation. Our results indicate that the D2 -5-HT1A complex possesses biochemical, pharmacological, and functional properties distinct from those of mono- and homomers. This result has implications for the development of improved pharmacotherapy for schizophrenia or other disorders (activating the heteromer might be cognitive enhancing, since it is expressed in frontal cortex) through the specific targeting of heterodimers. We reported the constitutive formation of D2 -5-HT1A heteromers, which possess biochemical, pharmacological, and functional properties distinct from those of mono- and homomers, as revealed by antipsychotics action. We also showed that these two receptors are co-expressed in mouse cortical neurons; therefore their potential to heterodimerize may comprise an essential target for the development of novel strategies for schizophrenia treatment.
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Affiliation(s)
- Sylwia Łukasiewicz
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Ewa Błasiak
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | | | - Marta Dziedzicka-Wasylewska
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
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10
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Bader M, Alenina N, Andrade-Navarro MA, Santos RA. MAS and its related G protein-coupled receptors, Mrgprs. Pharmacol Rev 2015; 66:1080-105. [PMID: 25244929 DOI: 10.1124/pr.113.008136] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The Mas-related G protein-coupled receptors (Mrgprs or Mas-related genes) comprise a subfamily of receptors named after the first discovered member, Mas. For most Mrgprs, pruriception seems to be the major function based on the following observations: 1) they are relatively promiscuous in their ligand specificity with best affinities for itch-inducing substances; 2) they are expressed in sensory neurons and mast cells in the skin, the main cellular components of pruriception; and 3) they appear in evolution first in tetrapods, which have arms and legs necessary for scratching to remove parasites or other noxious substances from the skin before they create harm. Because parasites coevolved with hosts, each species faced different parasitic challenges, which may explain another striking observation, the multiple independent duplication and expansion events of Mrgpr genes in different species as a consequence of parallel adaptive evolution. Their predominant expression in dorsal root ganglia anticipates additional functions of Mrgprs in nociception. Some Mrgprs have endogenous ligands, such as β-alanine, alamandine, adenine, RF-amide peptides, or salusin-β. However, because the functions of these agonists are still elusive, the physiologic role of the respective Mrgprs needs to be clarified. The best studied Mrgpr is Mas itself. It was shown to be a receptor for angiotensin-1-7 and to exert mainly protective actions in cardiovascular and metabolic diseases. This review summarizes the current knowledge about Mrgprs, their evolution, their ligands, their possible physiologic functions, and their therapeutic potential.
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Affiliation(s)
- Michael Bader
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany (M.B., N.A., M.A.A.-N.); Charité-University Medicine, Berlin, Germany (M.B.); Institute for Biology, University of Lübeck, Lübeck, Germany (M.B.); and Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Brazil (M.B., N.A., R.A.S.)
| | - Natalia Alenina
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany (M.B., N.A., M.A.A.-N.); Charité-University Medicine, Berlin, Germany (M.B.); Institute for Biology, University of Lübeck, Lübeck, Germany (M.B.); and Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Brazil (M.B., N.A., R.A.S.)
| | - Miguel A Andrade-Navarro
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany (M.B., N.A., M.A.A.-N.); Charité-University Medicine, Berlin, Germany (M.B.); Institute for Biology, University of Lübeck, Lübeck, Germany (M.B.); and Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Brazil (M.B., N.A., R.A.S.)
| | - Robson A Santos
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany (M.B., N.A., M.A.A.-N.); Charité-University Medicine, Berlin, Germany (M.B.); Institute for Biology, University of Lübeck, Lübeck, Germany (M.B.); and Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Brazil (M.B., N.A., R.A.S.)
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11
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Fujita W, Gomes I, Devi LA. Revolution in GPCR signalling: opioid receptor heteromers as novel therapeutic targets: IUPHAR review 10. Br J Pharmacol 2015; 171:4155-76. [PMID: 24916280 DOI: 10.1111/bph.12798] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 01/27/2014] [Accepted: 04/16/2014] [Indexed: 12/24/2022] Open
Abstract
GPCRs can interact with each other to form homomers or heteromers. Homomers involve interactions with the same receptor type while heteromers involve interactions between two different GPCRs. These receptor-receptor interactions modulate not only the binding but also the signalling and trafficking properties of individual receptors. Opioid receptor heteromerization has been extensively investigated with the objective of identifying novel therapeutic targets that are as potent as morphine but without the side effects associated with chronic morphine use. In this context, studies have described heteromerization between the different types of opioid receptors and between opioid receptors and a wide range of GPCRs including adrenoceptors, cannabinoid, 5-HT, metabotropic glutamate and sensory neuron-specific receptors. Recent advances in the field involving the generation of heteromer-specific reagents (antibodies or ligands) or of membrane-permeable peptides that disrupt the heteromer interaction are helping to elucidate the physiological role of opioid receptor heteromers and the contribution of the partner receptor to the side effects associated with opioid use. For example, studies using membrane-permeable peptides targeting the heteromer interface have implicated μ and δ receptor heteromers in the development of tolerance to morphine, and heteromers of μ and gastrin-releasing peptide receptors in morphine-induced itch. In addition, a number of ligands that selectively target opioid receptor heteromers exhibit potent antinociception with a decrease in the side effects commonly associated with morphine use. In this review, we summarize the latest findings regarding the biological and functional characteristics of opioid receptor heteromers both in vitro and in vivo.
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Affiliation(s)
- Wakako Fujita
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Solinski HJ, Gudermann T, Breit A. Pharmacology and signaling of MAS-related G protein-coupled receptors. Pharmacol Rev 2015; 66:570-97. [PMID: 24867890 DOI: 10.1124/pr.113.008425] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Signaling by heptahelical G protein-coupled receptors (GPCR) regulates many vital body functions. Consequently, dysfunction of GPCR signaling leads to pathologic states, and approximately 30% of all modern clinical drugs target GPCR. One decade ago, an entire new GPCR family was discovered, which was recently named MAS-related G protein-coupled receptors (MRGPR) by the HUGO Gene Nomenclature Committee. The MRGPR family consists of ∼40 members that are grouped into nine distinct subfamilies (MRGPRA to -H and -X) and are predominantly expressed in primary sensory neurons and mast cells. All members are formally still considered "orphan" by the Committee on Receptor Nomenclature and Drug Classification of the International Union of Basic and Clinical Pharmacology. However, several distinct peptides and amino acids are discussed as potential ligands, including β-alanine, angiotensin-(1-7), alamandine, GABA, cortistatin-14, and cleavage products of proenkephalin, pro-opiomelanocortin, prodynorphin, or proneuropeptide-FF-A. The full spectrum of biologic roles of all MRGPR is still ill-defined, but there is evidence pointing to a role of distinct MRGPR subtypes in nociception, pruritus, sleep, cell proliferation, circulation, and mast cell degranulation. This review article summarizes findings published in the last 10 years on the phylogenetic relationships, pharmacology, signaling, physiology, and agonist-promoted regulation of all MRGPR subfamilies. Furthermore, we highlight interactions between MRGPR and other hormonal systems, paying particular attention to receptor multimerization and morphine tolerance. Finally, we discuss the challenges the field faces presently and emphasize future directions of research.
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Affiliation(s)
- Hans Jürgen Solinski
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Gudermann
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Andreas Breit
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
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Tirupula KC, Desnoyer R, Speth RC, Karnik SS. Atypical signaling and functional desensitization response of MAS receptor to peptide ligands. PLoS One 2014; 9:e103520. [PMID: 25068582 PMCID: PMC4113456 DOI: 10.1371/journal.pone.0103520] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 07/01/2014] [Indexed: 11/19/2022] Open
Abstract
MAS is a G protein-coupled receptor (GPCR) implicated in multiple physiological processes. Several physiological peptide ligands such as angiotensin-(1-7), angiotensin fragments and neuropeptide FF (NPFF) are reported to act on MAS. Studies of conventional G protein signaling and receptor desensitization upon stimulation of MAS with the peptide ligands are limited so far. Therefore, we systematically analyzed G protein signals activated by the peptide ligands. MAS-selective non-peptide ligands that were previously shown to activate G proteins were used as controls for comparison on a common cell based assay platform. Activation of MAS by the non-peptide agonist (1) increased intracellular calcium and D-myo-inositol-1-phosphate (IP1) levels which are indicative of the activation of classical Gαq-phospholipase C signaling pathways, (2) decreased Gαi mediated cAMP levels and (3) stimulated Gα12-dependent expression of luciferase reporter. In all these assays, MAS exhibited strong constitutive activity that was inhibited by the non-peptide inverse agonist. Further, in the calcium response assay, MAS was resistant to stimulation by a second dose of the non-peptide agonist after the first activation has waned suggesting functional desensitization. In contrast, activation of MAS by the peptide ligand NPFF initiated a rapid rise in intracellular calcium with very weak IP1 accumulation which is unlike classical Gαq-phospholipase C signaling pathway. NPFF only weakly stimulated MAS-mediated activation of Gα12 and Gαi signaling pathways. Furthermore, unlike non-peptide agonist-activated MAS, NPFF-activated MAS could be readily re-stimulated the second time by the agonists. Functional assays with key ligand binding MAS mutants suggest that NPFF and non-peptide ligands bind to overlapping regions. Angiotensin-(1-7) and other angiotensin fragments weakly potentiated an NPFF-like calcium response at non-physiological concentrations (≥100 µM). Overall, our data suggest that peptide ligands induce atypical signaling and functional desensitization of MAS.
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Affiliation(s)
- Kalyan C. Tirupula
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Russell Desnoyer
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Robert C. Speth
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida, United States of America
| | - Sadashiva S. Karnik
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- * E-mail:
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Gupta A, Gomes I, Wardman J, Devi LA. Opioid receptor function is regulated by post-endocytic peptide processing. J Biol Chem 2014; 289:19613-26. [PMID: 24847082 DOI: 10.1074/jbc.m113.537704] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Most neuroendocrine peptides are generated in the secretory compartment by proteolysis of the precursors at classical cleavage sites consisting of basic residues by well studied endopeptidases belonging to the subtilisin superfamily. In contrast, a subset of bioactive peptides is generated by processing at non-classical cleavage sites that do not contain basic residues. Neither the peptidases responsible for non-classical cleavages nor the compartment involved in such processing has been well established. Members of the endothelin-converting enzyme (ECE) family are considered good candidate enzymes because they exhibit functional properties that are consistent with such a role. In this study we have explored a role for ECE2 in endocytic processing of δ opioid peptides and its effect on modulating δ opioid receptor function by using selective inhibitors of ECE2 that we had identified previously by homology modeling and virtual screening of a library of small molecules. We found that agonist treatment led to intracellular co-localization of ECE2 with δ opioid receptors. Furthermore, selective inhibitors of ECE2 and reagents that increase the pH of the acidic compartment impaired receptor recycling by protecting the endocytosed peptide from degradation. This, in turn, led to a substantial decrease in surface receptor signaling. Finally, we showed that treatment of primary neurons with the ECE2 inhibitor during recycling led to increased intracellular co-localization of the receptors and ECE2, which in turn led to decreased receptor recycling and signaling by the surface receptors. Together, these results support a role for differential modulation of opioid receptor signaling by post-endocytic processing of peptide agonists by ECE2.
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Affiliation(s)
- Achla Gupta
- From the Department of Pharmacology and Systems Therapeutics and
| | - Ivone Gomes
- From the Department of Pharmacology and Systems Therapeutics and
| | - Jonathan Wardman
- From the Department of Pharmacology and Systems Therapeutics and
| | - Lakshmi A Devi
- From the Department of Pharmacology and Systems Therapeutics and the Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029
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Gomes I, Fujita W, Chandrakala MV, Devi LA. Disease-specific heteromerization of G-protein-coupled receptors that target drugs of abuse. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 117:207-65. [PMID: 23663971 DOI: 10.1016/b978-0-12-386931-9.00009-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Drugs of abuse such as morphine or marijuana exert their effects through the activation of G-protein-coupled receptors (GPCRs), the opioid and cannabinoid receptors, respectively. Moreover, interactions between either of these receptors have been shown to be involved in the rewarding effects of drugs of abuse. Recent advances in the field, using a variety of approaches, have demonstrated that many GPCRs, including opioid, cannabinoid, and dopamine receptors, can form associations between different receptor subtypes or with other GPCRs to form heteromeric complexes. The formation of these complexes, in turn, leads to the modulation of the properties of individual protomers. The development of tools that can selectively disrupt GPCR heteromers as well as monoclonal antibodies that can selectively block signaling by specific heteromer pairs has indicated that heteromers involving opioid, cannabinoid, or dopamine receptors may play a role in various disease states. In this review, we describe evidence for opioid, cannabinoid, and dopamine receptor heteromerization and the potential role of GPCR heteromers in pathophysiological conditions.
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Affiliation(s)
- Ivone Gomes
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, USA
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Expression and distribution patterns of Mas-related gene receptor subtypes A-H in the mouse intestine: inflammation-induced changes. Histochem Cell Biol 2013; 139:639-58. [PMID: 23504129 DOI: 10.1007/s00418-013-1086-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2013] [Indexed: 12/20/2022]
Abstract
Mas-related gene (Mrg) receptors constitute a subfamily of G protein-coupled receptors that are implicated in nociception, and are as such considered potential targets for pain therapies. Furthermore, some Mrgs have been suggested to play roles in the regulation of inflammatory responses to non-immunological activation of mast cells and in mast cell-neuron communication. Except for MrgD, E and F, whose changed expression has been revealed during inflammation in the mouse intestine in our earlier studies, information concerning the remaining cloned mouse Mrg subtypes in the gastrointestinal tract during (patho) physiological conditions is lacking. Therefore, the present study aimed at identifying the presence and putative function of these remaining cloned Mrg subtypes (n = 19) in the (inflamed) mouse intestine. Using reverse transcriptase-PCR, quantitative-PCR and multiple immunofluorescence staining with commercial and newly custom-developed antibodies, we compared the ileum and the related dorsal root ganglia (DRG) of non-inflamed mice with those of two models of intestinal inflammation, i.e., intestinal schistosomiasis and 2,4,6-trinitrobenzene sulfonic acid-induced ileitis. In the non-inflamed ileum and DRG, the majority of the Mrg subtypes examined were sparsely expressed, showing a neuron-specific expression pattern. However, significant changes in the expression patterns of multiple Mrg subtypes were observed in the inflamed ileum; for instance, MrgA4, MrgB2and MrgB8 were expressed in a clearly increased number of enteric sensory neurons and in nerve fibers in the lamina propria, while de novo expression of MrgB10 was observed in enteric sensory neurons and in newly recruited mucosal mast cells (MMCs). The MrgB10 expressing MMCs were found to be in close contact with nerve fibers in the lamina propria. This is the first report on the expression of all cloned Mrg receptor subtypes in the (inflamed) mouse intestine. The observed changes in the expression and cellular localization of the Mrg subtypes suggest that these receptors are involved in the mediation of primary afferent responses, mast cell responses, and in neuroimmune communication during intestinal inflammation.
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17
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Solinski HJ, Petermann F, Rothe K, Boekhoff I, Gudermann T, Breit A. Human Mas-related G protein-coupled receptors-X1 induce chemokine receptor 2 expression in rat dorsal root ganglia neurons and release of chemokine ligand 2 from the human LAD-2 mast cell line. PLoS One 2013; 8:e58756. [PMID: 23505557 PMCID: PMC3591377 DOI: 10.1371/journal.pone.0058756] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 02/06/2013] [Indexed: 12/16/2022] Open
Abstract
Primate-specific Mas-related G protein-coupled receptors-X1 (MRGPR-X1) are highly enriched in dorsal root ganglia (DRG) neurons and induce acute pain. Herein, we analyzed effects of MRGPR-X1 on serum response factors (SRF) or nuclear factors of activated T cells (NFAT), which control expression of various markers of chronic pain. Using HEK293, DRG neuron-derived F11 cells and cultured rat DRG neurons recombinantly expressing human MRGPR-X1, we found activation of a SRF reporter gene construct and induction of the early growth response protein-1 via extracellular signal-regulated kinases-1/2 known to play a significant role in the development of inflammatory pain. Furthermore, we observed MRGPR-X1-induced up-regulation of the chemokine receptor 2 (CCR2) via NFAT, which is considered as a key event in the onset of neuropathic pain and, so far, has not yet been described for any endogenous neuropeptide. Up-regulation of CCR2 is often associated with increased release of its endogenous agonist chemokine ligand 2 (CCL2). We also found MRGPR-X1-promoted release of CCL2 in a human connective tissue mast cell line endogenously expressing MRGPR-X1. Thus, we provide first evidence to suggest that MRGPR-X1 induce expression of chronic pain markers in DRG neurons and propose a so far unidentified signaling circuit that enhances chemokine signaling by acting on two distinct yet functionally co-operating cell types. Given the important role of chemokine signaling in pain chronification, we propose that interruption of this signaling circuit might be a promising new strategy to alleviate chemokine-promoted pain.
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MESH Headings
- Animals
- Bradykinin/pharmacology
- Calcineurin/metabolism
- Calcium/metabolism
- Cell Line
- Chemokine CCL2/metabolism
- Early Growth Response Protein 1/genetics
- Early Growth Response Protein 1/metabolism
- Enzyme Activation/drug effects
- Ganglia, Spinal/metabolism
- Gene Expression Regulation/drug effects
- Genes, fos
- HEK293 Cells
- Humans
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Mast Cells/metabolism
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3/metabolism
- NFATC Transcription Factors/metabolism
- Peptide Fragments/pharmacology
- Rats
- Receptors, CCR2/genetics
- Receptors, CCR2/metabolism
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Sensory Receptor Cells/metabolism
- Serum Response Factor/metabolism
- Ternary Complex Factors/metabolism
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Affiliation(s)
- Hans Jürgen Solinski
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Franziska Petermann
- Department of Neurology, Klinikum rechts der Isar, Technical University Munich, Munich, Germany
| | - Kathrin Rothe
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ingrid Boekhoff
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Gudermann
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Andreas Breit
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
- * E-mail:
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18
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Southern C, Cook JM, Neetoo-Isseljee Z, Taylor DL, Kettleborough CA, Merritt A, Bassoni DL, Raab WJ, Quinn E, Wehrman TS, Davenport AP, Brown AJ, Green A, Wigglesworth MJ, Rees S. Screening β-arrestin recruitment for the identification of natural ligands for orphan G-protein-coupled receptors. ACTA ACUST UNITED AC 2013; 18:599-609. [PMID: 23396314 DOI: 10.1177/1087057113475480] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A variety of G-protein-coupled receptor (GPCR) screening technologies have successfully partnered a number of GPCRs with their cognate ligands. GPCR-mediated β-arrestin recruitment is now recognized as a distinct intracellular signaling pathway, and ligand-receptor interactions may show a bias toward β-arrestin over classical GPCR signaling pathways. We hypothesized that the failure to identify native ligands for the remaining orphan GPCRs may be a consequence of biased β-arrestin signaling. To investigate this, we assembled 10 500 candidate ligands and screened 82 GPCRs using PathHunter β-arrestin recruitment technology. High-quality screening assays were validated by the inclusion of liganded receptors and the detection and confirmation of these established ligand-receptor pairings. We describe a candidate endogenous orphan GPCR ligand and a number of novel surrogate ligands. However, for the majority of orphan receptors studied, measurement of β-arrestin recruitment did not lead to the identification of cognate ligands from our screening sets. β-Arrestin recruitment represents a robust GPCR screening technology, and ligand-biased signaling is emerging as a therapeutically exploitable feature of GPCR biology. The identification of cognate ligands for the orphan GPCRs and the extent to which receptors may exist to preferentially signal through β-arrestin in response to their native ligand remain to be determined.
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Affiliation(s)
- Craig Southern
- Medical Research Council Technology, Centre for Therapeutic Discovery, London, UK.
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19
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Richard-Lalonde M, Nagi K, Audet N, Sleno R, Amraei M, Hogue M, Balboni G, Schiller PW, Bouvier M, Hébert TE, Pineyro G. Conformational dynamics of Kir3.1/Kir3.2 channel activation via δ-opioid receptors. Mol Pharmacol 2012; 83:416-28. [PMID: 23175530 DOI: 10.1124/mol.112.081950] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
This study assessed how conformational information encoded by ligand binding to δ-opioid receptors (DORs) is transmitted to Kir3.1/Kir3.2 channels. Human embryonic kidney 293 cells were transfected with bioluminescence resonance energy transfer (BRET) donor/acceptor pairs that allowed us to evaluate independently reciprocal interactions among signaling partners. These and coimmunoprecipitation studies indicated that DORs, Gβγ, and Kir3 subunits constitutively interacted with one another. GαoA associated with DORs and Gβγ, but despite being part of the complex, no evidence of its direct association with the channel was obtained. DOR activation by different ligands left DOR-Kir3 interactions unmodified but modulated BRET between DOR-GαoA, DOR-Gβγ, GαoA-Gβγ, and Gβγ-Kir3 interfaces. Ligand-induced BRET changes assessing Gβγ-Kir3.1 subunit interaction 1) followed similar kinetics to those monitoring the GαoA-Gβγ interface, 2) displayed the same order of efficacy as those observed at the DOR-Gβγ interface, 3) were sensitive to pertussis toxin, and 4) were predictive of whether a ligand could evoke channel currents. Conformational changes at the Gβγ/Kir3 interface were lost when Kir3.1 subunits were replaced by a mutant lacking essential sites for Gβγ-mediated activation. Thus, conformational information encoded by agonist binding to the receptor is relayed to the channel via structural rearrangements that involve repositioning of Gβγ with respect to DORs, GαoA, and channel subunits. Further, the fact that BRET changes at the Gβγ-Kir3 interface are predictive of a ligand's ability to induce channel currents points to these conformational biosensors as screening tools for identifying GPCR ligands that induce Kir3 channel activation.
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20
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Solinski HJ, Zierler S, Gudermann T, Breit A. Human sensory neuron-specific Mas-related G protein-coupled receptors-X1 sensitize and directly activate transient receptor potential cation channel V1 via distinct signaling pathways. J Biol Chem 2012; 287:40956-71. [PMID: 23074220 DOI: 10.1074/jbc.m112.408617] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sensory neuron-specific Mas-related G protein-coupled receptors-X1 (MRGPR-X1) are primate-specific proteins that are exclusively expressed in primary sensory neurons and provoke pain in humans. Hence, MRGPR-X1 represent promising targets for future pain therapy, but signaling pathways activated by MRGPR-X1 are poorly understood. The transient receptor potential cation channel V1 (TRPV1) is also expressed in primary sensory neurons and detects painful stimuli such as protons and heat. G(q)-promoted signaling has been shown to sensitize TRPV1 via protein kinase C (PKC)-dependent phosphorylation. In addition, recent studies suggested TRPV1 activation via a G(q)-mediated mechanism involving diacylglycerol (DAG) or phosphatidylinositol-4,5-bisphosphate (PIP(2)). However, it is not clear if DAG-promoted TRPV1 activation occurs independently from classic TRPV1 activation modes induced by heat and protons. Herein, we analyzed putative functional interactions between MRGPR-X1 and TRPV1 in a previously reported F11 cell line stably over-expressing MRGPR-X1. First, we found that MRGPR-X1 sensitized TRPV1 to heat and protons in a PKC-dependent manner. Second, we observed direct MRGPR-X1-mediated TRPV1 activation independent of MRGPR-X1-induced Ca(2+)-release and PKC activity or other TRPV1 affecting enzymes such as lipoxygenase, extracellular signal-regulated kinases-1/2, sarcoma, or phosphoinositide 3-kinase. Investigating several TRPV1 mutants, we observed that removal of the TRPV1 binding site for DAG and of the putative PIP(2) sensor decreased MRGPR-X1-induced TRPV1 activation by 71 and 43%, respectively. Therefore, we demonstrate dual functional interactions between MRGPR-X1 and TRPV1, resulting in PKC-dependent TRPV1 sensitization and DAG/PIP(2)-mediated activation. The molecular discrimination between TRPV1 sensitization and activation may help improve the specificity of current pain therapies.
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Affiliation(s)
- Hans Jürgen Solinski
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München 80336 München, Germany
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22
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Differential association of receptor-Gβγ complexes with β-arrestin2 determines recycling bias and potential for tolerance of δ opioid receptor agonists. J Neurosci 2012; 32:4827-40. [PMID: 22492038 DOI: 10.1523/jneurosci.3734-11.2012] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Opioid tendency to generate analgesic tolerance has been previously linked to biased internalization. Here, we assessed an alternative possibility; whether tolerance of delta opioid receptor agonists (DORs) could be related to agonist-specific recycling. A first series of experiments revealed that DOR internalization by DPDPE and SNC-80 was similar, but only DPDPE induced recycling. We then established that the non-recycling agonist SNC-80 generated acute analgesic tolerance that was absent in mice treated with DPDPE. Furthermore, both agonists stabilized different conformations, whose distinct interaction with Gβγ subunits led to different modalities of β-arrestin2 (βarr2) recruitment. In particular, bioluminescence resonance energy transfer (BRET) assays revealed that sustained activation by SNC-80 drew the receptor C terminus in close proximity of the N-terminal domain of Gγ2, causing βarr2 to interact with receptors and Gβγ subunits. DPDPE moved the receptor C-tail away from the Gβγ dimer, resulting in βarr2 recruitment to the receptor but not in the vicinity of Gγ2. These differences were associated with stable DOR-βarr2 association, poor recycling, and marked desensitization following exposure to SNC-80, while DPDPE promoted transient receptor interaction with βarr2 and effective recycling, which conferred protection from desensitization. Together, these data indicate that DORs may adopt ligand-specific conformations whose distinct recycling properties determine the extent of desensitization and are predictive of analgesic tolerance. Based on these findings, we propose that the development of functionally selective DOR ligands that favor recycling could constitute a valid strategy for the production of longer acting opioid analgesics.
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Leskelä TT, Lackman JJ, Vierimaa MM, Kobayashi H, Bouvier M, Petäjä-Repo UE. Cys-27 variant of human δ-opioid receptor modulates maturation and cell surface delivery of Phe-27 variant via heteromerization. J Biol Chem 2011; 287:5008-20. [PMID: 22184124 DOI: 10.1074/jbc.m111.305656] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The important role of G protein-coupled receptor homo/heteromerization in receptor folding, maturation, trafficking, and cell surface expression has become increasingly evident. Here we investigated whether the human δ-opioid receptor (hδOR) Cys-27 variant that shows inherent compromised maturation has an effect on the behavior of the more common Phe-27 variant in the early secretory pathway. We demonstrate that hδOR-Cys-27 acts in a dominant negative manner and impairs cell surface delivery of the co-expressed hδOR-Phe-27 and impairs conversion of precursors to the mature form. This was demonstrated by metabolic labeling, Western blotting, flow cytometry, and confocal microscopy in HEK293 and human SH-SY5Y neuroblastoma cells using differentially epitope-tagged variants. The hδOR-Phe-27 precursors that were redirected to the endoplasmic reticulum-associated degradation were, however, rescued by a pharmacological chaperone, the opioid antagonist naltrexone. Co-immunoprecipitation of metabolically labeled variants revealed that both endoplasmic reticulum-localized precursors and mature receptors exist as homo/heteromers. The existence of homo/heteromers was confirmed in living cells by bioluminescence resonance energy transfer measurements, showing that the variants have a similar propensity to form homo/heteromers. By forming both homomers and heteromers, the hδOR-Cys-27 variant may thus regulate the levels of receptors at the cell surface, possibly leading to altered responsiveness to opioid ligands in individuals carrying the Cys-27 variant.
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Affiliation(s)
- Tarja T Leskelä
- Department of Anatomy and Cell Biology, Institute of Biomedicine, University of Oulu, FI-90014 Oulu, Finland
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24
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Vischer HF, Watts AO, Nijmeijer S, Leurs R. G protein-coupled receptors: walking hand-in-hand, talking hand-in-hand? Br J Pharmacol 2011; 163:246-60. [PMID: 21244374 DOI: 10.1111/j.1476-5381.2011.01229.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Most cells express a panel of different G protein-coupled receptors (GPCRs) allowing them to respond to at least a corresponding variety of extracellular ligands. In order to come to an integrative well-balanced functional response these ligand-receptor pairs can often cross-regulate each other. Although most GPCRs are fully capable to induce intracellular signalling upon agonist binding on their own, many GPCRs, if not all, appear to exist and function in homomeric and/or heteromeric assemblies for at least some time. Such heteromeric organization offers unique allosteric control of receptor pharmacology and function between the protomers and might even unmask 'new' features. However, it is important to realize that some functional consequences that are proposed to originate from heteromeric receptor interactions may also be observed due to intracellular crosstalk between signalling pathways of non-associated GPCRs.
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Affiliation(s)
- Henry F Vischer
- Leiden/Amsterdam Center for Drug Research (LACDR), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
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25
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Avula LR, Buckinx R, Alpaerts K, Costagliola A, Adriaensen D, Van Nassauw L, Timmermans JP. The effect of inflammation on the expression and distribution of the MAS-related gene receptors MrgE and MrgF in the murine ileum. Histochem Cell Biol 2011; 136:569-85. [DOI: 10.1007/s00418-011-0862-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2011] [Indexed: 12/31/2022]
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26
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Rozenfeld R, Gupta A, Gagnidze K, Lim MP, Gomes I, Lee-Ramos D, Nieto N, Devi LA. AT1R-CB₁R heteromerization reveals a new mechanism for the pathogenic properties of angiotensin II. EMBO J 2011; 30:2350-63. [PMID: 21540834 DOI: 10.1038/emboj.2011.139] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 04/05/2011] [Indexed: 12/23/2022] Open
Abstract
The mechanism of G protein-coupled receptor (GPCR) signal integration is controversial. While GPCR assembly into hetero-oligomers facilitates signal integration of different receptor types, cross-talk between Gαi- and Gαq-coupled receptors is often thought to be oligomerization independent. In this study, we examined the mechanism of signal integration between the Gαi-coupled type I cannabinoid receptor (CB(1)R) and the Gαq-coupled AT1R. We find that these two receptors functionally interact, resulting in the potentiation of AT1R signalling and coupling of AT1R to multiple G proteins. Importantly, using several methods, that is, co-immunoprecipitation and resonance energy transfer assays, as well as receptor- and heteromer-selective antibodies, we show that AT1R and CB(1)R form receptor heteromers. We examined the physiological relevance of this interaction in hepatic stellate cells from ethanol-administered rats in which CB(1)R is upregulated. We found a significant upregulation of AT1R-CB(1)R heteromers and enhancement of angiotensin II-mediated signalling, as compared with cells from control animals. Moreover, blocking CB(1)R activity prevented angiotensin II-mediated mitogenic signalling and profibrogenic gene expression. These results provide a molecular basis for the pivotal role of heteromer-dependent signal integration in pathology.
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Affiliation(s)
- Raphael Rozenfeld
- Department of Pharmacology and Systems Therapeutics, New York Mount Sinai School of Medicine, New York, NY, USA
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Smith NJ, Milligan G. Allostery at G protein-coupled receptor homo- and heteromers: uncharted pharmacological landscapes. Pharmacol Rev 2011; 62:701-25. [PMID: 21079041 DOI: 10.1124/pr.110.002667] [Citation(s) in RCA: 211] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
For many years seven transmembrane domain G protein-coupled receptors (GPCRs) were thought to exist and function exclusively as monomeric units. However, evidence both from native cells and heterologous expression systems has demonstrated that GPCRs can both traffic and signal within higher-order complexes. As for other protein-protein interactions, conformational changes in one polypeptide, including those resulting from binding of pharmacological ligands, have the capacity to alter the conformation and therefore the response of the interacting protein(s), a process known as allosterism. For GPCRs, allosterism across homo- or heteromers, whether dimers or higher-order oligomers, represents an additional topographical landscape that must now be considered pharmacologically. Such effects may offer the opportunity for novel therapeutic approaches. Allosterism at GPCR heteromers is particularly exciting in that it offers additional scope to provide receptor subtype selectivity and tissue specificity as well as fine-tuning of receptor signal strength. Herein, we introduce the concept of allosterism at both GPCR homomers and heteromers and discuss the various questions that must be addressed before significant advances can be made in drug discovery at these GPCR complexes.
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Affiliation(s)
- Nicola J Smith
- Molecular Pharmacology Laboratory,University Avenue, University of Glasgow, Glasgow, Scotland
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Albizu L, Moreno JL, González-Maeso J, Sealfon SC. Heteromerization of G protein-coupled receptors: relevance to neurological disorders and neurotherapeutics. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2011; 9:636-50. [PMID: 20632964 DOI: 10.2174/187152710793361586] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 03/30/2010] [Indexed: 11/22/2022]
Abstract
Because G protein-coupled receptors (GPCRs) are numerous, widely expressed and involved in major physiological responses, they represent a relevant therapeutic target for drug discovery, particularly regarding pharmacological treatments of neurological disorders. Among the biological phenomena regulating receptor function, GPCR heteromerization is an important emerging area of interest and investigation. There is increasing evidence showing that heteromerization contributes to the pharmacological heterogeneity of GPCRs by modulating receptor ontogeny, activation and recycling. Although in many cases the physiological relevance of receptor heteromerization has not been fully established, the unique pharmacological and functional properties of heteromers are likely to lead to new strategies in clinical medicine. This review describes the main GPCR heteromers and their implications for major neurological disorders such as Parkinson's disease, schizophrenia and addiction. A better understanding of molecular mechanisms underlying drug interactions related to the targeting of receptor heteromers could provide more specific and efficient therapeutic agents for the treatment of brain diseases.
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Affiliation(s)
- Laura Albizu
- Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, USA
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Abstract
The critical involvement of GPCRs (G-protein-coupled receptors) in nearly all physiological processes, and the presence of these receptors at the interface between the extracellular and the intracellular milieu, has positioned these receptors as pivotal therapeutic targets. Although a large number of drugs targeting GPCRs are currently available, significant efforts have been directed towards understanding receptor properties, with the goal of identifying and designing improved receptor ligands. Recent advances in GPCR pharmacology have demonstrated that different ligands binding to the same receptor can activate discrete sets of downstream effectors, a phenomenon known as 'ligand-directed signal specificity', which is currently being explored for drug development due to its potential therapeutic advantage. Emerging studies suggest that GPCR responses can also be modulated by contextual factors, such as interactions with other GPCRs. Association between different GPCR types leads to the formation of complexes, or GPCR heteromers, with distinct and unique signalling properties. Some of these heteromers activate discrete sets of signalling effectors upon activation by the same ligand, a phenomenon termed 'heteromer-directed signalling specificity'. This has been shown to be involved in the physiological role of receptors and, in some cases, in disease-specific dysregulation of a receptor effect. Hence targeting GPCR heteromers constitutes an emerging strategy to select receptor-specific responses and is likely to be useful in achieving specific beneficial therapeutic effects.
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Davis MP. Opioid receptor targeting ligands for pain management: a review and update. Expert Opin Drug Discov 2010; 5:1007-22. [DOI: 10.1517/17460441.2010.511473] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Gupta A, Mulder J, Gomes I, Rozenfeld R, Bushlin I, Ong E, Lim M, Maillet E, Junek M, Cahill CM, Harkany T, Devi LA. Increased abundance of opioid receptor heteromers after chronic morphine administration. Sci Signal 2010; 3:ra54. [PMID: 20647592 DOI: 10.1126/scisignal.2000807] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The mu and delta types of opioid receptors form heteromers that exhibit pharmacological and functional properties distinct from those of homomeric receptors. To characterize these complexes in the brain, we generated antibodies that selectively recognize the mu-delta heteromer and blocked its in vitro signaling. With these antibodies, we showed that chronic, but not acute, morphine treatment caused an increase in the abundance of mu-delta heteromers in key areas of the central nervous system that are implicated in pain processing. Because of its distinct signaling properties, the mu-delta heteromer could be a therapeutic target in the treatment of chronic pain and addiction.
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Affiliation(s)
- Achla Gupta
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, NY 10029, USA
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Solinski HJ, Boekhoff I, Bouvier M, Gudermann T, Breit A. Sensory neuron-specific MAS-related gene-X1 receptors resist agonist-promoted endocytosis. Mol Pharmacol 2010; 78:249-59. [PMID: 20424127 DOI: 10.1124/mol.110.063867] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Human sensory neuron-specific mas-related gene X1 receptors (hMrgX1s) belong to the superfamily of G protein-coupled receptors (GPCRs), bind cleavage products of pro-enkephalin with high affinity, and have been suggested to participate in pain sensation. Murine or rat MrgC receptors exhibit high similarities with hMrgX1 in terms of expression pattern, sequence homology, and binding profile. Therefore, rodents have been used as an in vivo model to explore the physiological functions and pharmacodynamics of the hMrgX1. Agonist-promoted receptor endocytosis significantly affects the pharmacodynamics of a GPCR but is not yet investigated for hMrgX1. Therefore, we analyzed the effects of prolonged agonist exposure on cell surface protein levels of hMrgX1 and murine or rat MrgC in human embryonic kidney 293, Cos, F11, and ND-C cells. We observed that hMrgX1 are resistant and both MrgC are prone to agonist-promoted receptor endocytosis. In Cos cells, coexpression of beta-arrestins strongly enhanced endocytosis of murine MrgC but did not alter cell surface expression of hMrgX1 receptors. These data define the hMrgX1 as one of the few members within the superfamily of GPCRs whose signaling is not regulated by agonist-promoted endocytosis and reveal species-specific differences in the regulation of Mrg receptor signaling. Given the importance of receptor endocytosis for the pharmacodynamics of a given ligand, our results may have a strong impact on the development of future drugs that suppose to control pain in humans but were tested in rodents.
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Affiliation(s)
- Hans Jürgen Solinski
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, 80336 München, Germany
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Tao PL, Law PY, Loh HH. Search for the "ideal analgesic" in pain treatment by engineering the mu-opioid receptor. IUBMB Life 2010; 62:103-11. [PMID: 20039371 DOI: 10.1002/iub.292] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The myriad of side effects that associate with morphine has been problematic in the clinical use to manage moderate to severe pain. It has been the holy grail of the pharmacologists to develop a compound, or treatment paradigm that could retain the analgesic effect of the drug as eliminating or reducing the side effects, mainly the tolerance and addiction development associates with chronic usage of the drug. In our earlier receptor structure/activities studies, we discovered an unique mutation of a conserved Ser in the fourth transmembrane domain of the opioid receptor that the alkaloid antagonist could activate the receptor. On the basis of this initial finding, we decide to explore the possibility of using virus to deliver the mutant mu-opioid receptor at the various sites of the nociceptive pathway and induce the antinociceptive responses with the systemic administration of opioid antagonists. In this article, we will summarize the progress of such approach and the probable advantages over the conventional approach of drug development in the treatment of chronic pain.
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Affiliation(s)
- Pao-Luh Tao
- Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan, Republic of China
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Rozenfeld R, Devi LA. Receptor heteromerization and drug discovery. Trends Pharmacol Sci 2010; 31:124-30. [PMID: 20060175 PMCID: PMC2834828 DOI: 10.1016/j.tips.2009.11.008] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 11/25/2009] [Accepted: 11/25/2009] [Indexed: 10/20/2022]
Abstract
G-protein-coupled receptors (GPCRs) are membrane proteins that convert extracellular information into intracellular signals. They are involved in many biological processes and therefore represent powerful targets to modulate physiological and pathological states. Recent studies have demonstrated that GPCR activity is regulated by several mechanisms. Among these, protein-protein interactions (and in particular interactions with other receptors leading to heteromerization) has been shown to have an important role in modulating GPCR function. This has expanded their repertoire of signaling and added a new level of regulation to their physiological roles. Emerging studies provide evidence for tissue-specific and disease-specific receptor heteromerization. This suggests that heteromers represent novel drug targets for the identification of selective compounds with potentially fewer side-effects.
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Affiliation(s)
- Raphael Rozenfeld
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY10029, USA
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35
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Hudson BD, Hébert TE, M. Kelly ME. Ligand- and Heterodimer-Directed Signaling of the CB1 Cannabinoid Receptor. Mol Pharmacol 2009; 77:1-9. [DOI: 10.1124/mol.109.060251] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Guan R, Feng X, Wu X, Zhang M, Zhang X, Hébert TE, Segaloff DL. Bioluminescence resonance energy transfer studies reveal constitutive dimerization of the human lutropin receptor and a lack of correlation between receptor activation and the propensity for dimerization. J Biol Chem 2009; 284:7483-94. [PMID: 19147490 DOI: 10.1074/jbc.m809150200] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Previous studies from our laboratory using co-immunoprecipitation techniques suggested that the human lutropin receptor (hLHR) constitutively self-associates into dimers/oligomers and that agonist treatment of cells either increased hLHR dimerization/oligomerization and/or stabilized hLHR dimers/oligomers to detergent solubilization (Tao, Y. X., Johnson, N. B., and Segaloff, D. L. (2004) J. Biol. Chem. 279, 5904-5914). In this study, bioluminescence resonance energy transfer (BRET(2)) analyses confirmed that the hLHR constitutively self-associates in living cells. After subcellular fractionation, hLHR dimers/oligomers were detected in both the plasma membrane and endoplasmic reticulum (ER). Further evidence supporting the constitutive formation of hLHR dimer/oligomers in the ER is provided by data showing homodimerization of misfolded hLHR mutants that are retained in the ER. These mutants, when co-expressed with wild-type receptor, are shown by BRET(2) to heterodimerize, accounting for their dominant-negative effects on cell surface receptor expression. Hormone desorption assays using intact cells demonstrate allosterism between hLHR protomers, indicating functional cell surface hLHR dimers. However, quantitative BRET(2) analyses in intact cells indicate a lack of effect of agonist on the propensity of the hLHR to dimerize. Using purified plasma membranes, human chorionic gonadotropin was similarly observed to have no effect on the BRET(2) signal. An examination of the propensity for constitutively active and signaling inactive hLHR mutants to dimerize further showed no correlation between dimerization and the activation state of the hLHR. Taken altogether, our data suggest that hLHR dimers/oligomers are formed early in the biosynthetic pathway in the ER, are constitutively expressed on the plasma membrane, and are not affected by the activation state of the hLHR.
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Affiliation(s)
- Rongbin Guan
- Department of Molecular Biophysics and Physiology, The Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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Dalrymple MB, Pfleger KDG, Eidne KA. G protein-coupled receptor dimers: functional consequences, disease states and drug targets. Pharmacol Ther 2008; 118:359-71. [PMID: 18486226 DOI: 10.1016/j.pharmthera.2008.03.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Accepted: 03/14/2008] [Indexed: 10/22/2022]
Abstract
With an ever-expanding need for reliable therapeutic agents that are highly effective and exhibit minimal deleterious side effects, a greater understanding of the mechanisms underlying G protein-coupled receptor (GPCR) regulation is fundamental. GPCRs comprise more than 30% of all therapeutic drug targets and it is likely that this will only increase as more orphan GPCRs are identified. The past decade has seen a dramatic shift in the prevailing concept of how GPCRs function, in particular the growing acceptance that GPCRs are capable of interacting with one another at a molecular level to form complexes, with significantly different pharmacological properties to their monomeric selves. While the ability of like-receptors to associate and form homodimers raises some interesting mechanistic issues, the possibility that unlike-receptors could heterodimerise in certain tissue types, producing a functionally unique signalling complex that binds specific ligands, provides an invaluable opportunity to refine and redefine pharmacological interventions with greater specificity and efficacy.
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Affiliation(s)
- Matthew B Dalrymple
- Laboratory for Molecular Endocrinology - GPCRs, Western Australian Institute for Medical Research and Centre for Medical Research, University of Western Australia, Nedlands, Perth, WA 6009, Australia
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Audet N, Galés C, Archer-Lahlou E, Vallières M, Schiller PW, Bouvier M, Pineyro G. Bioluminescence resonance energy transfer assays reveal ligand-specific conformational changes within preformed signaling complexes containing delta-opioid receptors and heterotrimeric G proteins. J Biol Chem 2008; 283:15078-88. [PMID: 18381293 DOI: 10.1074/jbc.m707941200] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heptahelical receptors communicate extracellular information to the cytosolic compartment by binding an extensive variety of ligands. They do so through conformational changes that propagate to intracellular signaling partners as the receptor switches from a resting to an active conformation. This active state has been classically considered unique and responsible for regulation of all signaling pathways controlled by a receptor. However, recent functional studies have challenged this notion and called for a paradigm where receptors would exist in more than one signaling conformation. This study used bioluminescence resonance energy transfer assays in combination with ligands of different functional profiles to provide in vivo physical evidence of conformational diversity of delta-opioid receptors (DORs). DORs and alpha(i1)beta(1)gamma(2) G protein subunits were tagged with Luc or green fluorescent protein to produce bioluminescence resonance energy transfer pairs that allowed monitoring DOR-G protein interactions from different vantage points. Results showed that DORs and heterotrimeric G proteins formed a constitutive complex that underwent structural reorganization upon ligand binding. Conformational rearrangements could not be explained by a two-state model, supporting the idea that DORs adopt ligand-specific conformations. In addition, conformational diversity encoded by the receptor was conveyed to the interaction among heterotrimeric subunits. The existence of multiple active receptor states has implications for the way we conceive specificity of signal transduction.
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Affiliation(s)
- Nicolas Audet
- Centre de Recherche Fernand-Seguin, Hôpital Louis-H. Lafontaine, Montréal, Quebec, Canada
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Milligan G. A day in the life of a G protein-coupled receptor: the contribution to function of G protein-coupled receptor dimerization. Br J Pharmacol 2008; 153 Suppl 1:S216-29. [PMID: 17965750 PMCID: PMC2268067 DOI: 10.1038/sj.bjp.0707490] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 08/21/2007] [Accepted: 09/06/2007] [Indexed: 02/07/2023] Open
Abstract
G protein-coupled receptors are one of the most actively studied families of proteins. However, despite the ubiquity of protein dimerization and oligomerization as a structural and functional motif in biology, until the last decade they were generally considered as monomeric, non-interacting polypeptides. For the metabotropic glutamate-like group of G protein-coupled receptors, it is now firmly established that they exist and function as dimers or, potentially, even within higher-order structures. Despite some evidence continuing to support the view that rhodopsin-like G protein-coupled receptors are predominantly monomers, many recent studies are consistent with the dimerization/oligomerization of such receptors. Key roles suggested for dimerization of G protein-coupled receptors include control of protein maturation and cell surface delivery and providing the correct framework for interactions with both hetero-trimeric G proteins and arrestins to allow signal generation and its termination. As G protein-coupled receptors are the most targeted group of proteins for the development of therapeutic small molecule medicines, recent indications that hetero-dimerization between co-expressed G protein-coupled receptors may be a common process offers the potential for the development of more selective and tissue restricted medicines. However, many of the key experiments have, so far, been limited to model cell systems. Priorities for the future include the generation of tools and reagents able to identify unequivocally potential G protein-coupled receptor hetero-dimers in native tissues and detailed analyses of the influence of hetero-dimerization on receptor function and pharmacology.
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Affiliation(s)
- G Milligan
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, Scotland, UK.
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Chakera A, Seeber RM, John AE, Eidne KA, Greaves DR. The Duffy Antigen/Receptor for Chemokines Exists in an Oligomeric Form in Living Cells and Functionally Antagonizes CCR5 Signaling through Hetero-Oligomerization. Mol Pharmacol 2008; 73:1362-70. [DOI: 10.1124/mol.107.040915] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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Hager U, Hein A, Lennerz J, Zimmermann K, Neuhuber W, Reeh P. Morphological characterization of rat Mas-related G-protein-coupled receptor C and functional analysis of agonists. Neuroscience 2008; 151:242-54. [DOI: 10.1016/j.neuroscience.2007.09.085] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 09/06/2007] [Accepted: 09/24/2007] [Indexed: 02/05/2023]
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Abstract
This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, United States.
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Huang Q, Acha V, Yow R, Schneider E, Sardar DK, Hornsby PJ. Bioluminescence measurements in mice using a skin window. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:054012. [PMID: 17994900 DOI: 10.1117/1.2795567] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Studies of bioluminescence in living animals, such as cell-based biosensor applications, require measurement of light at different wavelengths, but accurate light measurement is impeded by absorption by tissues at wavelengths<600 nm. We present a novel approach to this problem--the use of a plastic window in the skin/body wall of mice--that permits measurements of light produced by bioluminescent cells transplanted into the kidney. The cells coexpressed firefly luciferase (FLuc), a vasopressin receptor--Renilla luciferase (RLuc) fusion protein, and a GFP2-beta-arrestin2 fusion protein. Following coadministration of two luciferase substrates, native coelenterazine and luciferin, bioluminescence is measured via the window using fiber optics and a photon counter. Light emission from the two different luciferases, FLuc and RLuc, is readily distinguishable using appropriate optical filters. When coelenterazine 400a is administered, bioluminescence resonance energy transfer (BRET) occurs between the RLuc and GFP2 fusion proteins and is detected by the use of suitable filters. Following intraperitoneal injection of vasopressin, there is a marked increase in BRET. When rapid and accurate measurement of light from internal organs is required, rather than spatial imaging of bioluminescence, the combination of skin/body wall window and fiber optic light measurement will be advantageous.
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Affiliation(s)
- Qin Huang
- University of Texas Health Science Center, Department of Physiology and Sam and Ann Barshop Institute for Longevity and Aging Studies, San Antonio, Texas 78245, USA
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Springael JY, Urizar E, Costagliola S, Vassart G, Parmentier M. Allosteric properties of G protein-coupled receptor oligomers. Pharmacol Ther 2007; 115:410-8. [PMID: 17655934 DOI: 10.1016/j.pharmthera.2007.06.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Accepted: 06/07/2007] [Indexed: 11/18/2022]
Abstract
Allosteric regulation of ligand binding is a well-established mechanism regulating the function of G protein-coupled receptors (GPCR). Allosteric modulators have been considered so far as molecules binding to an allosteric site, distinct from that of the reference ligand (orthosteric site), and able to modulate the binding affinity at the orthosteric site and/or the signaling properties resulting from orthosteric site occupancy. Given that most GPCR are known to form dimers or higher order oligomers, we explored whether allosteric interactions could also occur between protomers within oligomeric arrays, thereby influencing binding and signaling receptor properties. Two main conclusions emerged from such studies. First, allosteric modulators can affect one receptor by binding to another receptor within a dimeric or oligomeric complex. Second, allosteric modulators might act on a given receptor by targeting the "orthosteric site" in another receptor of the complex. Allosteric regulation within di(oligo)mers thus implies that the pharmacological properties of a given receptor subtype can be influenced by the array of dimerization partners coexpressed in each particular cell type. Ligands could thus act as agonists or antagonists on 1 receptor, while modulating allosterically the function of a variety of other receptors to which they do not bind directly. Allosteric regulation across GPCR oligomeric interfaces is expected to greatly influence the practice of pharmacology. It will likely affect the design of drug discovery programs, which rely mostly on the overexpression of the receptor of interest in a cell line, thereby focusing on homo-oligomers and ignoring the potential effects of other partners.
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Affiliation(s)
- Jean-Yves Springael
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), Université Libre de Bruxelles, Campus Erasme, 808 Route de Lennik, Elsevier Inc, B-1070, Brussels, Belgium
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Requirements and ontology for a G protein-coupled receptor oligomerization knowledge base. BMC Bioinformatics 2007; 8:177. [PMID: 17537266 PMCID: PMC1904246 DOI: 10.1186/1471-2105-8-177] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Accepted: 05/30/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND G Protein-Coupled Receptors (GPCRs) are a large and diverse family of membrane proteins whose members participate in the regulation of most cellular and physiological processes and therefore represent key pharmacological targets. Although several bioinformatics resources support research on GPCRs, most of these have been designed based on the traditional assumption that monomeric GPCRs constitute the functional receptor unit. The increase in the frequency and number of reports about GPCR dimerization/oligomerization and the implication of oligomerization in receptor function makes necessary the ability to store and access information about GPCR dimers/oligomers electronically. RESULTS We present here the requirements and ontology (the information scheme to describe oligomers and associated concepts and their relationships) for an information system that can manage the elements of information needed to describe comprehensively the phenomena of both homo- and hetero-oligomerization of GPCRs. The comprehensive information management scheme that we plan to use for the development of an intuitive and user-friendly GPCR-Oligomerization Knowledge Base (GPCR-OKB) is the result of a community dialog involving experimental and computational colleagues working on GPCRs. CONCLUSION Our long term goal is to disseminate to the scientific community organized, curated, and detailed information about GPCR dimerization/oligomerization and its related structural context. This information will be reported as close to the data as possible so the user can make his own judgment on the conclusions drawn for a particular study. The requirements and ontology described here will facilitate the development of future information systems for GPCR oligomers that contain both computational and experimental information about GPCR oligomerization. This information is freely accessible at http://www.gpcr-okb.org.
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Milligan G. G protein-coupled receptor dimerisation: Molecular basis and relevance to function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:825-35. [PMID: 17069751 DOI: 10.1016/j.bbamem.2006.09.021] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 09/25/2006] [Accepted: 09/26/2006] [Indexed: 12/21/2022]
Abstract
The belief that G protein-coupled receptors exist and function as monomeric, non-interacting species has been largely supplanted in recent years by evidence, derived from a range of approaches, that indicate they can form dimers and/or higher-order oligomeric complexes. Key roles for receptor homo-dimerisation include effective quality control of protein folding prior to plasma membrane delivery and interactions with hetero-trimeric G proteins. Growing evidence has also indicated the potential for many co-expressed G protein-coupled receptors to form hetero-dimers/oligomers. The relevance of this to physiology and function is only beginning to be unravelled but may offer great potential for more selective therapeutic intervention.
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Affiliation(s)
- Graeme Milligan
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, Scotland, UK.
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Chapter 12 Principles of G-Protein Coupled Receptor Modeling for Drug Discovery. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/s1574-1400(07)03012-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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