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Moye LS, Siegersma K, Dripps I, Witkowski W, Mangutov E, Wang D, Scherrer G, Pradhan AA. Delta opioid receptor regulation of calcitonin gene-related peptide dynamics in the trigeminal complex. Pain 2021; 162:2297-2308. [PMID: 33605657 PMCID: PMC8730473 DOI: 10.1097/j.pain.0000000000002235] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 02/08/2021] [Indexed: 12/14/2022]
Abstract
ABSTRACT Migraine is highly prevalent and is the sixth leading cause worldwide for years lost to disability. Therapeutic options specifically targeting migraine are limited, and delta opioid receptor (DOP) agonists were recently identified as a promising pharmacotherapy. The mechanisms by which DOPs regulate migraine are currently unclear. Calcitonin gene-related peptide (CGRP) has been identified as an endogenous migraine trigger and plays a critical role in migraine initiation and susceptibility. The aim of this study was to determine the behavioral effects of DOP agonists on the development of chronic migraine-associated pain and to investigate DOP coexpression with CGRP and CGRP receptor (CGRPR) in the trigeminal system. Chronic migraine-associated pain was induced in mice through repeated intermittent injection of the known human migraine trigger, nitroglycerin. Chronic nitroglycerin resulted in severe chronic cephalic allodynia which was prevented with cotreatment of the DOP-selective agonist, SNC80. In addition, a corresponding increase in CGRP expression in the trigeminal ganglia and trigeminal nucleus caudalis was observed after chronic nitroglycerin, an augmentation that was blocked by SNC80. Moreover, DOP was also upregulated in these head pain-processing regions following the chronic migraine model. Immunohistochemical analysis of the trigeminal ganglia revealed coexpression of DOP with CGRP as well as with a primary component of the CGRPR, RAMP1. In the trigeminal nucleus caudalis, DOP was not coexpressed with CGRP but was highly coexpressed with RAMP1 and calcitonin receptor-like receptor. These results suggest that DOP agonists inhibit migraine-associated pain by attenuating CGRP release and blocking pronociceptive signaling of the CGRPR.
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Affiliation(s)
- Laura S Moye
- Department of Psychiatry, University of Illinois at Chicago
| | | | - Isaac Dripps
- Department of Psychiatry, University of Illinois at Chicago
| | | | | | - Dong Wang
- Department of Anesthesiology, Perioperative and Pain Medicine, Department of Neurosurgery, Department of Molecular and Cellular Physiology, Stanford Neurosciences Institute, Stanford University, Palo Alto, CA 94304, USA
| | - Grégory Scherrer
- Department of Cell Biology and Physiology, UNC Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- New York Stem Cell Foundation – Robertson Investigator
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2
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Dripps IJ, Bertels Z, Moye LS, Tipton AF, Siegersma K, Baca SM, Kieffer BL, Pradhan AA. Forebrain delta opioid receptors regulate the response of delta agonist in models of migraine and opioid-induced hyperalgesia. Sci Rep 2020; 10:17629. [PMID: 33077757 PMCID: PMC7573615 DOI: 10.1038/s41598-020-74605-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 09/30/2020] [Indexed: 12/14/2022] Open
Abstract
Delta opioid receptor (DOR) agonists have been identified as a promising novel therapy for headache disorders. DORs are broadly expressed in several peripheral and central regions important for pain processing and mood regulation; and it is unclear which receptors regulate headache associated symptoms. In a model of chronic migraine-associated pain using the human migraine trigger, nitroglycerin, we observed increased expression of DOR in cortex, hippocampus, and striatum; suggesting a role for these forebrain regions in the regulation of migraine. To test this hypothesis, we used conditional knockout mice with DORs deleted from forebrain GABAergic neurons (Dlx-DOR), and investigated the outcome of this knockout on the effectiveness of the DOR agonist SNC80 in multiple headache models. In DOR loxP controls SNC80 blocked the development of acute and chronic cephalic allodynia in the chronic nitroglycerin model, an effect that was lost in Dlx-DOR mice. In addition, the anti-allodynic effects of SNC80 were lost in a model of opioid induced hyperalgesia/medication overuse headache in Dlx-DOR conditional knockouts. In a model reflecting negative affect associated with migraine, SNC80 was only effective in loxP controls and not Dlx-DOR mice. Similarly, SNC80 was ineffective in the cortical spreading depression model of migraine aura in conditional knockout mice. Taken together, these data indicate that forebrain DORs are necessary for the action of DOR agonists in relieving headache-related symptoms and suggest that forebrain regions may play an important role in migraine modulation.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Analgesics, Opioid/therapeutic use
- Animals
- Benzamides/pharmacology
- Benzamides/therapeutic use
- Cortical Spreading Depression/drug effects
- Cortical Spreading Depression/physiology
- Disease Models, Animal
- GABAergic Neurons/drug effects
- GABAergic Neurons/metabolism
- Hyperalgesia/chemically induced
- Hyperalgesia/drug therapy
- Hyperalgesia/metabolism
- Mice
- Mice, Knockout
- Migraine Disorders/chemically induced
- Migraine Disorders/drug therapy
- Migraine Disorders/metabolism
- Nitroglycerin
- Piperazines/pharmacology
- Piperazines/therapeutic use
- Prosencephalon/drug effects
- Prosencephalon/metabolism
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
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Affiliation(s)
- Isaac J Dripps
- Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor Street (MC 912), Chicago, IL, 60612, USA
| | - Zachariah Bertels
- Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor Street (MC 912), Chicago, IL, 60612, USA
| | - Laura S Moye
- Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor Street (MC 912), Chicago, IL, 60612, USA
| | - Alycia F Tipton
- Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor Street (MC 912), Chicago, IL, 60612, USA
| | - Kendra Siegersma
- Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor Street (MC 912), Chicago, IL, 60612, USA
| | - Serapio M Baca
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, USA
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, USA
| | - Brigitte L Kieffer
- Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal, Canada
| | - Amynah A Pradhan
- Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor Street (MC 912), Chicago, IL, 60612, USA.
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3
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Ozawa A, Brunori G, Cippitelli A, Toll N, Schoch J, Kieffer BL, Toll L. Analysis of the distribution of spinal NOP receptors in a chronic pain model using NOP-eGFP knock-in mice. Br J Pharmacol 2018; 175:2662-2675. [PMID: 29582417 PMCID: PMC6003644 DOI: 10.1111/bph.14225] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 02/16/2018] [Accepted: 03/19/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND PURPOSE The nociceptin/orphanin FQ opioid peptide (NOP) receptor system plays a significant role in the regulation of pain. This system functions differently in the spinal cord and brain. The mechanism by which the NOP receptor agonists regulate pain transmission in these regions is not clearly understood. Here, we investigate the peripheral and spinal NOP receptor distribution and antinociceptive effects of intrathecal nociceptin/orphanin FQ (N/OFQ) in chronic neuropathic pain. EXPERIMENTAL APPROACH We used immunohistochemistry to determine changes in NOP receptor distribution triggered by spinal nerve ligation (SNL) using NOP-eGFP knock-in mice. Antinociceptive effects of intrathecal N/OFQ on SNL-mediated allodynia and heat/cold hyperalgesia were assessed in wild-type mice. KEY RESULTS NOP-eGFP immunoreactivity was decreased by SNL in the spinal laminae I and II outer, regions that mediate noxious heat stimuli. In contrast, immunoreactivity of NOP-eGFP was unchanged in the ventral border of lamina II inner, which is an important region for the development of allodynia. NOP-eGFP expression was also decreased in a large number of primary afferents in the L4 dorsal root ganglion (DRG) of SNL mice. However, SNL mice showed increased sensitivity, compared to sham animals to the effects of i.t administered N/OFQ with respect to mechanical as well as thermal stimuli. CONCLUSIONS AND IMPLICATIONS Our findings suggest that the spinal NOP receptor system attenuates injury-induced hyperalgesia by direct inhibition of the projection neurons in the spinal cord that send nociceptive signals to the brain and not by inhibiting presynaptic terminals of DRG neurons in the superficial lamina.
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Affiliation(s)
- Akihiko Ozawa
- Torrey Pines Institute for Molecular StudiesPort St. LucieFL34987USA
| | - Gloria Brunori
- Torrey Pines Institute for Molecular StudiesPort St. LucieFL34987USA
- Department of Biomedical Science, Charles E. Schmidt College of MedicineFlorida Atlantic UniversityBoca RatonFL33431USA
| | - Andrea Cippitelli
- Torrey Pines Institute for Molecular StudiesPort St. LucieFL34987USA
| | - Nicholas Toll
- Torrey Pines Institute for Molecular StudiesPort St. LucieFL34987USA
| | - Jennifer Schoch
- Torrey Pines Institute for Molecular StudiesPort St. LucieFL34987USA
| | - Brigitte L Kieffer
- Douglas Research Center, Department of Psychiatry, Faculty of MedicineMcGill UniversityMontrealQCH4H 1R3Canada
| | - Lawrence Toll
- Torrey Pines Institute for Molecular StudiesPort St. LucieFL34987USA
- Department of Biomedical Science, Charles E. Schmidt College of MedicineFlorida Atlantic UniversityBoca RatonFL33431USA
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Hayashi K, Yamashita R, Takami R, Matsui T, Gotou M, Nishimoto T, Kobayashi H. Strategy for Identification of Phosphorylation Levels of Low Abundance Proteins in Vivo for Which Antibodies Are not Available. J Cardiovasc Dev Dis 2017; 4:jcdd4040017. [PMID: 29367546 PMCID: PMC5753118 DOI: 10.3390/jcdd4040017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 09/22/2017] [Accepted: 09/30/2017] [Indexed: 12/05/2022] Open
Abstract
Protein function is mainly modulated by dynamic reversible or irreversible post-translational modifications. Among them, the identification of protein phosphorylation sites and changes in phosphorylation levels in vivo are of considerable interest for a better understanding of the protein function. Thus, effective strategies for the quantitative determination of phosphorylation degrees for low abundant proteins, for which antibodies are not available, are required in order to evaluate the functional regulation of proteins attributed to phosphorylation. In this study, we used the heart β1-adrenergic receptor (Adrb1) as a model protein and developed FLAG-Adrb1 knock-in mice, in which the FLAG tag was inserted at the N-terminus of Adrb1. The phosphorylation sites and levels of Adrb1 in the heart were elucidated by immuno-affinity purification followed by quantitative mass spectrometry analysis using ion intensity ratio of the phosphorylated peptide versus corresponding unphosphorylated peptide. The phosphorylation levels at Ser274 and Ser462 of Adrb1 were approximately 0.25 and 0.0023. This effective strategy should be useful for not only analyzing site-specific phosphorylation levels of target proteins, but also quantifying the expression levels of proteins of interest when appropriate antibodies are not available.
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Affiliation(s)
- Kozo Hayashi
- Integrated Technology Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555 Fujisawa, Japan.
| | - Ryo Yamashita
- Integrated Technology Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555 Fujisawa, Japan.
| | - Ritsuko Takami
- Integrated Technology Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555 Fujisawa, Japan.
| | - Toshikatsu Matsui
- Cardiovascular and Metabolic Drug Discovery Unit, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555 Fujisawa, Japan.
| | - Masamitsu Gotou
- Integrated Technology Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555 Fujisawa, Japan.
| | - Tomoyuki Nishimoto
- Cardiovascular and Metabolic Drug Discovery Unit, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555 Fujisawa, Japan.
| | - Hiroyuki Kobayashi
- Integrated Technology Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555 Fujisawa, Japan.
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5
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Madariaga-Mazón A, Marmolejo-Valencia AF, Li Y, Toll L, Houghten RA, Martinez-Mayorga K. Mu-Opioid receptor biased ligands: A safer and painless discovery of analgesics? Drug Discov Today 2017; 22:1719-1729. [PMID: 28743488 DOI: 10.1016/j.drudis.2017.07.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/24/2017] [Accepted: 07/07/2017] [Indexed: 12/19/2022]
Abstract
Biased activation of G-protein-coupled receptors (GPCRs) is shifting drug discovery efforts and appears promising for the development of safer drugs. The most effective analgesics to treat acute pain are agonists of the μ opioid receptor (μ-OR), a member of the GPCR superfamily. However, the analgesic use of opioid drugs, such as morphine, is hindered by adverse effects. Only a few μ-OR agonists have been reported to selectively activate the Gi over β-arrestin signaling pathway, resulting in lower gastrointestinal dysfunction and respiratory suppression. Here, we discuss the strategies that led to the development of biased μ-OR agonists, and potential areas for improvement, with an emphasis on structural aspects of the ligand-receptor recognition process.
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Affiliation(s)
- Abraham Madariaga-Mazón
- Instituto de Química, Universidad Nacional Autónoma de México, Av. Universidad 3000, Mexico City 04510, Mexico
| | - Andrés F Marmolejo-Valencia
- Instituto de Química, Universidad Nacional Autónoma de México, Av. Universidad 3000, Mexico City 04510, Mexico
| | - Yangmei Li
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, FL 34987, USA
| | - Lawrence Toll
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, FL 34987, USA
| | - Richard A Houghten
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, FL 34987, USA
| | - Karina Martinez-Mayorga
- Instituto de Química, Universidad Nacional Autónoma de México, Av. Universidad 3000, Mexico City 04510, Mexico.
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6
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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: 86] [Impact Index Per Article: 12.3] [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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7
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Foster SR, Bräuner-Osborne H. Investigating Internalization and Intracellular Trafficking of GPCRs: New Techniques and Real-Time Experimental Approaches. Handb Exp Pharmacol 2017; 245:41-61. [PMID: 29018878 DOI: 10.1007/164_2017_57] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The ability to regulate the interaction between cells and their extracellular environment is essential for the maintenance of appropriate physiological function. For G protein-coupled receptors (GPCRs), this regulation occurs through multiple mechanisms that provide spatial and temporal control for signal transduction. One of the major mechanisms for GPCR regulation involves their endocytic trafficking, which serves to internalize the receptors from the plasma membrane and thereby attenuate G protein-dependent signaling. However, there is accumulating evidence to suggest that GPCRs can signal independently of G proteins, as well as from intracellular compartments including endosomes. It is in this context that receptor internalization and intracellular trafficking have attracted renewed interest within the GPCR field. In this chapter, we will review the current understanding and methodologies that have been used to investigate internalization and intracellular signaling of GPCRs, with a particular focus on emerging real-time techniques. These recent developments have improved our understanding of the complexities of GPCR internalization and intracellular signaling and suggest that the broader biological relevance and potential therapeutic implications of these processes remain to be explored.
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Affiliation(s)
- Simon R Foster
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Hans Bräuner-Osborne
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
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